As discussed with Dan, here are the different diff files to apply to the cvs tree and a description of the content of each file.
The diff files are located here: http://sourceforge.net/projects/vmonseur.u/files/libexif-gtk/

Description updates1.diff

 summary: technical changes + internationalisation changes

 - whitespace changes
 - cleaning of useless comments
 - call of bindtextdomain in required places (to avoid changing API to have a global call)
 - added missing gettext definition in gtk-options.c
 - added missing internationalisation of options[i].name in gtk-options.c
 - added LOCALEDIR in Makefile.am
 - changed G_LOG_DOMAIN from libexif to libexif-gtk
 - call to gtk_set_locale removed from test-libexif-gtk.c (already done in gtk-init)
 - call to bind_textdomain_codeset added in test-libexif-gtk.c

Description updates2.diff

 summary: changes to remove gtk2 deprecated calls and
          adapt the code for both gtk2 and gtk3 following the documentation:

 - deprecated GtkFileSelection has been replaced by GtkFileChooser API
 - accesses to some internal gtk variables via pointer have been replaced by accesses via accessor functions
 - GtkTooltips has been deprecated in gtk 2.12 in favor of the new GtkTooltip API so make the code conditional for both APIs
 - when possible transform deprecated symbols into new ones valid for both gtk2 and gtk3
 - remove individual includes...
 - ...otherwise condition the code for gtk2/gtk3

 Note: after those changes, the code is compatible for both gtk2 and gtk3
       but the autotools have not yet been adapted to allow for the gtk3 build.

Description updates3.diff

 summary: autotools adapted to gtk2 or gtk3
          fixed bug in deletion of notebook pages
          fr translation updated

 - autogen.sh: added
 - Changelog: updated
 - NEWS: updated
 - README: updated
 - TODO: created
 - configure.ac: version/revision changed
 - configure.ac: added option --with--gtk3
 - Makefile.am: changed to build with gtk2 or gtk3
 - libexif-gtk.pc: specific file generated when building with gtk2 or gtk3
 - libexif-gtk-uninstalled.pc: specific file generated when building with gtk2 or gtk3
 - fixed segfault bug when removing pages of notebook
 - Language tag added in .po files
 - French translation fully updated
 - gtk-options.c added in POTFILES.in

patched with these commands starting from the cvs:
  cvs -z3 -d:pserver:anonymous@libexif.cvs.sourceforge.net:/cvsroot/libexif co -P libexif-gtk
  patch -p2 -i updates1.diff
  patch -p2 -i updates2.diff
  patch -p2 -i updates3.diff