mutex_trylock returns 0 (success) if locked and non-zero (error) if not

locked.  Make the non-threaded case always return "locked", similar to
the non-threaded case for mutex_lock.

This commit was SVN r9956.

opal/threads/mutex.h

@@ -187,9 +187,9 @@ static inline bool opal_set_using_threads(bool have)
 #endif
 
 #if OMPI_HAVE_THREAD_SUPPORT
-#define OPAL_THREAD_TRYLOCK(mutex)   (opal_using_threads() ? opal_mutex_trylock(mutex) : 1)
+#define OPAL_THREAD_TRYLOCK(mutex)   (opal_using_threads() ? opal_mutex_trylock(mutex) : 0)
 #else
-#define OPAL_THREAD_TRYLOCK(mutex)   1
+#define OPAL_THREAD_TRYLOCK(mutex)   0
 #endif