http://bugs.gentoo.org/465780

Same for all of memcpy(), memset(), strlen() and strcpy():

apngasm.c:141:11: warning: incompatible implicit declaration of built-in function ‘memcpy’ [enabled by default]

--- apngasm.c
+++ apngasm.c
@@ -29,6 +29,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include "png.h"     /* original (unpatched) libpng is ok */
 #include "zlib.h"