For pthread_mutex_trylock() call on owned error-check or non-portable

adaptive mutex, return EDEADLK as required by POSIX.  The
pthread_mutex_lock() is already compliant.

Tested by:	Guy Yur <guyyur@gmail.com>
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)

lib/libthr/thread/thr_mutex.c

@@ -850,8 +850,11 @@ mutex_self_trylock(struct pthread_mutex *m)
 
 	switch (PMUTEX_TYPE(m->m_flags)) {
 	case PTHREAD_MUTEX_ERRORCHECK:
-	case PTHREAD_MUTEX_NORMAL:
 	case PTHREAD_MUTEX_ADAPTIVE_NP:
+		ret = EDEADLK;
+		break;
+
+	case PTHREAD_MUTEX_NORMAL:
 		ret = EBUSY;
 		break;