clib2 Code

- Changed the execvp() test program to reflect how the corrected
execvp() function works.

- Added the missing fdim() and fdimf() functions to the build
makefiles. The OS4 build makefile was missing lrint() and
lrintf(). Ouch.

- execve() now checks if an abort signal arrives while it's trying
to read the first line of a script, or looking for an executable
on an assignment path.

- execve() no longer directly calls exit(), but a function which can be
replaced by the user. If that function __execve_exit() does not call
exit but just returns to the caller without doing anything, execve()
will return the caller with the return code of the RunCommand()
function.

- Small corrections...

- That's setlocale and not setlocate.

- Hid setlocale and execvp_test

- execve() now actually works!

- Added the "execvp_test" program.

- Added the POSIX exec() family functions, based upon code contributed
by Henning Nielsen Lund. Thank you very much!

- atoll() no longer sets 'errno' directly but now calls __set_errno()
instead.

- Fixed to compile correctly.

- Changed how multi-volume assignments are handled by execve().