Remove stdio.h from utils.h. Manually include stdio.h if using the

TRACEF() macro from utils.h

include/ucore/utils.h

@@ -2,7 +2,6 @@
 #define UC_UTILS_H_
 
 #include <stddef.h>
-#include <stdio.h>
 
 //Gnerate a compiler error if the compile time
 //constant expression fails
@@ -74,6 +73,7 @@ const typeof( ((const type *)0)->member ) *__mptr = (ptr);    \
 
 
 #ifdef DEBUG
+    //include <stdio.h> if using the TRACEF() macro
     #define TRACEF(fmt, ...)\
     do { \
         fprintf(stdout, "%s (%s)\t" fmt, UC_SRC_LOCATION,  __FUNCTION__,  ##__VA_ARGS__);\

src/iomux_impl.c

@@ -1,6 +1,6 @@
 #include <stdlib.h>
 #include <string.h>
-#include <string.h>
+#include <stdio.h>
 #include <assert.h>
 #include "ucore/clock.h"
 #include "ucore/backtrace.h"

test/test_heapsort.c

@@ -1,4 +1,5 @@
 #include <check.h>
+#include <stdio.h>
 #include "ucore/utils.h"
 #include "ucore/heapsort.h"