No, Eric, it still does not work here. My source is always C. Even in the simplest

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <glib.h>
#include <glib/gstdio.h>
#include <glib/gprintf.h>

#include <gst/gst.h>
#include <gst/pbutils/pbutils.h>

int main (int argc, char **argv) {
    gst_init (&argc, &argv);

    return 0;
}

the first 3 #includes resolve OK (bovine) but the latter 5 are "unknown".

It compiles using

libtool --mode=link gcc -Wall test.c -o test $(pkg-config --cflags --libs glib-2.0 gstreamer-1.0 gstreamer-pbutils-1.0) -ldl

Maybe my .emacs is errorneous? (I found no instructions on how to write a correct .emacs)

;; -*-Emacs-Lisp-*-

;; This file is designed to be re-evaled; use the variable first-time
;; to avoid any problems with this.
(defvar first-time t
  "Flag signifying this is the first time that .emacs has been evaled")

;; Load CEDET.
;; See cedet/common/cedet.info for configuration details.
;; IMPORTANT: Tou must place this *before* any CEDET component (including
;; EIEIO) gets activated by another package (Gnus, auth-source, ...).
(load-file "/home/sergei/cedet/cedet-devel-load.el")

;; Add further minor-modes to be enabled by semantic-mode.
;; See doc-string of `semantic-default-submodes' for other things
;; you can use here.


;; All these should be added before enabling semantic-mode
; activates CEDET's context menu that is bound to right mouse button
(add-to-list 'semantic-default-submodes 'global-cedet-m3-minor-mode t)

; To enable Semanticdb
(add-to-list 'semantic-default-submodes 'global-semanticdb-minor-mode t)

; enables automatic bookmarking of tags that you edited, so you can return to them 
; later with the semantic-mrub-switch-tags command
(add-to-list 'semantic-default-submodes 'global-semantic-mru-bookmark-mode t)

; activates highlighting of first line for current tag (function, class, etc.)
(add-to-list 'semantic-default-submodes 'global-semantic-highlight-func-mode t)

; activates mode when name of current tag will be shown in top line of buffer
(add-to-list 'semantic-default-submodes 'global-semantic-stickyfunc-mode t)

; activates use of separate styles for tags decoration (depending on tag's class);
; these styles are defined in the semantic-decoration-styles list
(add-to-list 'semantic-default-submodes 'global-semantic-decoration-mode t)

; activates highlighting of local names that are the same as name of tag under cursor
(add-to-list 'semantic-default-submodes 'global-semantic-idle-local-symbol-highlight-mode t)

; activates automatic parsing of source code in the idle time
(add-to-list 'semantic-default-submodes 'global-semantic-idle-scheduler-mode t)

; activates displaying of possible name completions in the idle time;
; requires that global-semantic-idle-scheduler-mode was enabled
(add-to-list 'semantic-default-submodes 'global-semantic-idle-completions-mode t)

; activates displaying of information about current tag in the idle time;
; requires that global-semantic-idle-scheduler-mode was enabled
(add-to-list 'semantic-default-submodes 'global-semantic-idle-summary-mode t)


;; Enable Semantic
(semantic-mode 1)

;; You can also explicitly specify additional directories for searching of include 
;; files (and these directories also could be different for specific modes).
;; To add some directory to list of system include paths, you can use the 
;; semantic-add-system-include command — it accepts two parameters: 
;; a string with the path to include files, and symbol, representing name of the 
;; major mode, for which this path will be used. For example, to add Boost header 
;; files for C++ mode, you need to add following code:
;;(semantic-add-system-include "~/exp/include/boost_1_37" 'c++-mode)
(semantic-add-system-include "/usr/include/glib-2.0" 'c-mode)
(semantic-add-system-include "/usr/lib/x86_64-linux-gnu/glib-2.0/include" 'c-mode)
(semantic-add-system-include "/usr/include/gstreamer-1.0" 'c-mode)


;; To enable more advanced functionality for name completion, etc
(require 'semantic/ia)

;; When using GCC for programming in C & C++, then Semantic can automatically find 
;; directories, where system include files are stored
(require 'semantic/bovine/gcc)

;;;; The Semantic package can be integrated with the imenu package. 
; This lead to creation of a menu with a list of functions, variables, 
; and other tags. To enable this feature you need to add following code 
; into your initialization file:

(defun my-semantic-hook ()
  (imenu-add-to-menubar "TAGS"))
(add-hook 'semantic-init-hooks 'my-semantic-hook)


;;;; Semanticdb can also use databases generated by external utilities: 
; gtags (from GNU Global), exubertant ctags, ebrowse & cscope. 
; To activate this functionality you can use the following code (please, 
; note that these commands may fail if you have no utilities installed, 
; or have an incorrect versions of them — that's why they a wrapped into when):
;; if you want to enable support for gnu global
(when (cedet-gnu-global-version-check t)
  (semanticdb-enable-gnu-global-databases 'c-mode)
  (semanticdb-enable-gnu-global-databases 'c++-mode))


;; Enable EDE (Project Management) features
(global-ede-mode 1)


;; Some commands have no standard key bindings, so it's better 
; to select key bindings, that are comfortable to you, and bind 
; commands to them, like this (only for standalone CEDET):
(defun my-cedet-hook ()
  (local-set-key [(control return)] 'semantic-ia-complete-symbol)
  (local-set-key "\C-c?" 'semantic-ia-complete-symbol-menu)
  (local-set-key "\C-c>" 'semantic-complete-analyze-inline)
  (local-set-key "\C-cp" 'semantic-analyze-proto-impl-toggle))
(add-hook 'c-mode-common-hook 'my-cedet-hook)


;;;; Linus Torvalds's:
;(defun linux-c-mode ()
;  "C mode with adjusted defaults for use with the Linux kernel."
;  (interactive)
;  (c-mode)
;  (setq c-indent-level 8)
;  (setq c-brace-imaginary-offset 0)
;  (setq c-brace-offset -8)
;  (setq c-argdecl-indent 8)
;  (setq c-label-offset -8)
;  (setq c-continued-statement-offset 8)
;  (setq indent-tabs-mode nil)
;  (setq tab-width 8))

;; (setq-default tab-width 8)


;; Does not work
;(defun my-tab-hook ()
;  (setq c-indent-level 8)
;  (setq c-brace-imaginary-offset 0)
;  (setq c-brace-offset -8)
;  (setq c-argdecl-indent 8)
;  (setq c-label-offset -8)
;  (setq c-continued-statement-offset 8)
;  (setq indent-tabs-mode nil)
;  (setq tab-width 8))
;(add-hook 'c-mode-hook 'my-tab-hook)


(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(cua-mode t nil (cua-base)))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )

;;;; Enable context menu with 'mouse-3'
(global-cedet-m3-minor-mode 1)
;; You could bind this menu to a key with a command such
;; as this which binds it to 'C-c SPC':
(define-key cedet-m3-mode-map "\C-c " 'cedet-m3-menu-kbd)
;; The context menu pulls together helpful context aware suggestions
;; from semantic, or templates to insert with SRecode.  It also suggests
;; compilation steps to take from EDE

;;;; See c-offset-alist as well!!!
(setq c-basic-offset 4)