Fix a few more warnings

Some are important, e.g. the seemingly harmless braces around if with dprintf,
since that dprintf is defined as empty, will screw things up and grab the next
line

Change-Id: Ie5e1cf813178ad708ff42ae5e477fbc96034471c

executer/user/libsched_yield.c

@@ -11,7 +11,9 @@
 
 typedef int (*int_void_fn)(void);
 
+#if 0
 static int_void_fn orig_sched_yield = 0;
+#endif
 
 int sched_yield(void)
 {