libpng: bump version

package/libpng/libpng.mk

@@ -21,7 +21,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 # USA
 
-LIBPNG_VERSION:=1.2.16
+LIBPNG_VERSION:=1.2.25
 LIBPNG_DIR:=$(BUILD_DIR)/libpng-$(LIBPNG_VERSION)
 LIBPNG_SITE:=http://$(BR2_SOURCEFORGE_MIRROR).dl.sourceforge.net/sourceforge/libpng
 LIBPNG_SOURCE:=libpng-$(LIBPNG_VERSION).tar.bz2