lib/replace: fix PTHREAD_MUTEX_ROBUST fallback to PTHREAD_MUTEX_ROBUST_NP on solaris 11

lib/replace: fix PTHREAD_MUTEX_ROBUST fallback to PTHREAD_MUTEX_ROBUST_NP on solaris 11

Without this we got the following defines in config.h:

   #define HAVE_DECL_PTHREAD_MUTEXATTR_SETROBUST_NP 1
   #define HAVE_DECL_PTHREAD_MUTEX_CONSISTENT_NP 1
   #define HAVE_PTHREAD_MUTEXATTR_SETROBUST 1
   #define HAVE_PTHREAD_MUTEX_CONSISTENT 1
   #define HAVE_ROBUST_MUTEXES 1
   #define USE_TDB_MUTEX_LOCKING 1

And the build failed with PTHREAD_MUTEX_ROBUST being unknown.

Note that PTHREAD_MUTEX_ROBUST and PTHREAD_MUTEX_ROBUST_NP are enum values
while they're defines on solaris 11
BUG: https://bugzilla.samba.org/show_bug.cgi?id=11319

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>