libpng: bump to version 1.4.7

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/libpng/libpng.mk

@@ -3,7 +3,7 @@
 # libpng (Portable Network Graphic library)
 #
 #############################################################
-LIBPNG_VERSION = 1.4.5
+LIBPNG_VERSION = 1.4.7
 LIBPNG_SERIES = 14
 LIBPNG_SITE = http://$(BR2_SOURCEFORGE_MIRROR).dl.sourceforge.net/sourceforge/libpng
 LIBPNG_SOURCE = libpng-$(LIBPNG_VERSION).tar.bz2