protect against undefined symbol

dtool/src/dtoolbase/mutexPosixImpl.I

@@ -23,9 +23,8 @@ MutexPosixImpl() {
   TAU_PROFILE("MutexPosixImpl::MutexPosixImpl", " ", TAU_USER);
   pthread_mutexattr_t attr;
   pthread_mutexattr_init(&attr);
-#ifdef PTHREAD_MUTEX_DEFAULT
-  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_DEFAULT);
-#endif
+  // The symbol PTHREAD_MUTEX_DEFAULT isn't always available?
+  // pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_DEFAULT);
   int result = pthread_mutex_init(&_lock, &attr);
   pthread_mutexattr_destroy(&attr);
   assert(result == 0);

panda/src/pipeline/contextSwitch_posix_src.c

@@ -160,9 +160,8 @@ alloc_thread_context() {
 
   pthread_mutexattr_t attr;
   pthread_mutexattr_init(&attr);
-#ifdef PTHREAD_MUTEX_DEFAULT
-  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_DEFAULT);
-#endif
+  // The symbol PTHREAD_MUTEX_DEFAULT isn't always available?
+  //  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_DEFAULT);
   int result = pthread_mutex_init(&context->_ready_mutex, &attr);
   pthread_mutexattr_destroy(&attr);