Revert "Remove some compiler warnings"

This reverts commit 76671249d6.

src/gos/gos_x_threads.c

@@ -122,6 +122,7 @@ void gfxSleepMilliseconds(delaytime_t ms) {
 	case TIME_INFINITE:
 		while(1)
 			gfxYield();
+		return;
 	}
 
 	// Convert our delay to ticks
@@ -143,6 +144,7 @@ void gfxSleepMicroseconds(delaytime_t ms) {
 	case TIME_INFINITE:
 		while(1)
 			gfxYield();
+		return;
 	}
 
 	// Convert our delay to ticks

src/gtimer/gtimer.c

@@ -109,7 +109,7 @@ static DECLARE_THREAD_FUNCTION(GTimerThreadHandler, arg) {
 		lastTime = tm;
 		gfxMutexExit(&mutex);
 	}
-//	THREAD_RETURN(0);
+	THREAD_RETURN(0);
 }
 
 void _gtimerInit(void)