clib2 Code

- Fixed the startup build target directory names.

- Changed how the startup code is built for the different library flavours,
and which files this involves.

- Final version bump before release.

- Added a hopefully enlightening comment on the subtleties of semaphore
locking in the stdio_fflush.c file.

- The stdio locking in fcntl() wasn't working correctly. Fixed.

- Made the clearerr(), feof() and ferror() macros thread-safe.

- Small tweaks to fix GCC 68k compiler warnings.

- Added more code and changes contributed by Peter Bengtsson, thank you
very much! This includes the following:

- Added SSIZE_MAX to <limits.h>.

- Added <sys/uio.h>, readv() and writev().

- Cut back the soft link resolution code in lstat().

- In <fcntl.h> O_NDELAY is now an alias for O_NONBLOCK.

- Added <complex.h>, carg(), cargf(), cargl(), cimag(), cimagf(),
cimagl(), conj(), conjf(), conjl(), creal(), crealf() and creall().

Note that the C99 support for the complex floating point data
types is limited to GCC 3.x for now.

- Added va_copy() to <stdarg.h>.

- Added _Exit() to <stdlib.h>.

- Added <stdbool.h>.

- Added vfscanf() to <stdio.h>.

- We now call IsInteractive() rather than send a type ACTION_DISK_INFO
to a likely console handler file's MsgPort.

- Invoking fstat() on what maps to a con-handler stream now produces
information identifying it as a character special file. Side-effect:
if the input/output went to a CON:/AUTO window, that window will
pop open and stay open.

- File descriptors produced by dup() or dup2() now work exactly like
the original file descriptors they are duplicates of. I modified the
function which maps file descriptor numbers to file descriptor
table entries to return the table entries of the original files.

- In the thread-safe library, duplicated stdin/stdout/stderr
descriptors now work like the "real" ones. This is true even if
the "real" ones were closed and only their former aliases remain.