Add mq (message queue) to test infrastructure.

Add mtx (mutex) to test infrastructure, in order to avoid bootstrapping
complications that would result from directly using malloc_mutex.

Rename test infrastructure's thread abstraction from je_thread to thd.

Fix some header ordering issues.

include/jemalloc/internal/tsd.h

@@ -348,7 +348,7 @@ a_name##_tsd_get_wrapper(void)						\
 		wrapper = tsd_init_check_recursion(			\
 		    &a_name##_tsd_init_head, &block);			\
 		if (wrapper)						\
-		    return wrapper;					\
+		    return (wrapper);					\
 		wrapper = (a_name##_tsd_wrapper_t *)			\
 		    malloc_tsd_malloc(sizeof(a_name##_tsd_wrapper_t));	\
 		block.data = wrapper;					\