Move malloc_wrappers.c to tests/common

tests/common/malloc_wrappers.h

@@ -0,0 +1,7 @@
+#include <stdlib.h>
+
+void* malloc_with_check(size_t size);
+void free_with_check(void *mem);
+void* counting_realloc(void *ptr, size_t size);
+void counting_free(void *ptr);
+size_t get_alloc_count();