Add checks to "configure" to see whether _POSIX_PTHREAD_SEMANTICS needs
to be defined to get the right number of arguments in the prototypes for
getpwuid_r(). Solaris' default implementation conforms to POSIX.1c
Draft 6, rather than the final POSIX.1c spec. The standards-compliant
version can be used by defining _POSIX_PTHREAD_SEMANTICS.
This change also adds the file "compat/check_getpwuid.c", which
configure uses to perform its check, and modifies compat/compat.h to
define _POSIX_PTHREAD_SEMANTICS if configure detected it was needed.
Signed-off-by: Vladimir Marek <vlmarek@volny.cz>
