Ensure config.h is included first, bug#89336.

config.h may define ABI-specific macros, especially for AIX,
so has to be included before any system header - via fcint.h.

https://bugs.freedesktop.org/show_bug.cgi?id=89336

src/fcarch.c

@@ -21,10 +21,9 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <stdio.h>
-
 #include "fcint.h"
 #include "fcarch.h"
+#include <stdio.h>
 
 FC_ASSERT_STATIC (1 == sizeof (char));
 FC_ASSERT_STATIC (2 == sizeof (FcChar16));