Made pthread mutex recursive.

include/bx/mutex.h

@@ -69,7 +69,10 @@ namespace bx
 	public:
 		Mutex()
 		{
-			pthread_mutex_init(&m_handle, NULL);
+			pthread_mutexattr_t attr;
+			pthread_mutexattr_init(&attr);
+			pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+			pthread_mutex_init(&m_handle, &attr);
 		}
 
 		~Mutex()