cmake,common/RWLock: check for libpthread extensions

cmake,common/RWLock: check for libpthread extensions

pthread_rwlockattr_setkind_np() is a GNU extension of libpthread. and
Tianshan Qu pointed out, we cannot use
ifdef(PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP) to detect the
availability of this function, because it's an enum not a macro. so,
like other *_np() extensions, we check this one also using cmake at
the configure phase.

Reported-by: Tianshan Qu <tianshan@xsky.com>
Signed-off-by: Kefu Chai <kchai@redhat.com>