Update libpng to version 1.6.3

Change-Id: I86cb46ec376eb41324b82d2875757aeda734c5c1
diff --git a/libpng.pc.in b/libpng.pc.in
new file mode 100644
index 0000000..3e7e2c5
--- /dev/null
+++ b/libpng.pc.in
@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+
+Name: libpng
+Description: Loads and saves PNG files
+Version: @PNGLIB_VERSION@
+Libs: -L${libdir} -lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+Libs.private: @LIBS@
+Cflags: -I${includedir}