Add fix for test on windows.

Author: luqmana

src/test/run-make/extern-fn-with-packed-struct/test.c

@@ -1,3 +1,5 @@
+// Pragma needed cause of gcc bug on windows: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52991
+#pragma pack(1)
 struct __attribute__((packed)) Foo {
     char a;
     short b;