util/mallocHelper: add missing #include guards

Author: CarterLi

src/util/mallocHelper.h

@@ -1,3 +1,8 @@
+#pragma once
+
+#ifndef FASTFETCH_INCLUDED_UTIL_MALLOC_HELPER
+#define FASTFETCH_INCLUDED_UTIL_MALLOC_HELPER
+
 #include <stdlib.h>
 #include <assert.h>
 
@@ -9,3 +14,5 @@ static inline void ffWrapFree(void* pPtr)
 }
 
 #define FF_AUTO_FREE __attribute__((__cleanup__(ffWrapFree)))
+
+#endif