clib2 Code

- Removed an unnecessary (STRPTR) cast.

- Added some documenting comments to the source code.

- __get_default_file() called __fd_unlock() without having called
__fd_lock() first. Ouch.

- Removed an unnecessary pair of __fd_lock()..__fd_unlock() calls from
ttyname_r().

- Unlink is now reentrant, or at least thread-safe.

- You can now make unlink() stop after a failed deletion attempt which
failed because the object to be deleted was reported as being "in use".
The libunix.a variant defaults to report the deletion to have succeeded
under these circumstances and later tries to delete the files marked
for deletion. See <dos.h> for a brief documentation of how to change
the behaviour.

- Added the base_dir_nametest test program.

- basename() and dirname() can no longer return NULL. They truncate the
resulting path name instead. This is done so because some code that
calls basename() or dirname() does not check if the function's return
value is NULL.

- Forgot to update chown() to use the same bug fix as fchown().

- The SetOwner() fall-back code for Kickstart 2.04 was passing the wrong
parameters to the file system. The first (dp_Arg1) should have been
zero. Ouch.

- Got rid of some more compiler warnings by introducing function prototypes
which were missing and by casting pointers to the expected types.

- Corrected a couple more compiler warnings caused by mutable/constant
string pointer assignments.