Update libpng from 1.6.3 to 1.6.10

Change-Id: I76e81e7fd267d15991cd342c5caeb2fe77964ebf
diff --git a/tests/pngimage-quick b/tests/pngimage-quick
new file mode 100755
index 0000000..2d4b5db
--- /dev/null
+++ b/tests/pngimage-quick
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec ./pngimage --log "${srcdir}/contrib/pngsuite/"*.png