Added semaphore support to MIT-pthreads.


Docs/manual.texi:
  Updated benchmark data
configure.in:
  Portability fix for compiling MIT-pthreads with gcc 3.0.x
  (Still not perfect)
include/my_semaphore.h:
  Cleanup
mit-pthreads/Changes-mysql:
  Added semaphore support
mit-pthreads/include/Makefile.inc:
  Added semaphore support
mit-pthreads/include/pthread/ac-types.h:
  Added semaphore support
mit-pthreads/pthreads/GNUmakefile.inc:
  Added semaphore support
mit-pthreads/pthreads/Makefile.inc:
  Added semaphore support
mit-pthreads/stdio/xprintf.c:
  Added semaphore support
mysql-test/r/rpl_alter.result:
  Fixed test results after merge with 3.23
sql/ha_isam.cc:
  Fixed core dump after merge
sql/ha_isam.h:
  Fixed core dump after merge
sql/mini_client.cc:
  P