Contribs: minor update to 1.2.39

No major changes, but I prefer to stay close to upstream, for obvious reasons.

extras/contrib/src/packages.mak

@@ -135,7 +135,7 @@ VCDIMAGER_VERSION=0.7.23
 VCDIMAGER_URL=$(GNU)/vcdimager/vcdimager-$(VCDIMAGER_VERSION).tar.gz
 CDIO_VERSION=0.80
 CDIO_URL=$(GNU)/libcdio/libcdio-$(CDIO_VERSION).tar.gz
-PNG_VERSION=1.2.37
+PNG_VERSION=1.2.39
 PNG_URL=$(SF)/libpng/libpng-$(PNG_VERSION).tar.bz2
 GPGERROR_VERSION=1.7
 #GPGERROR_URL=$(VIDEOLAN)/testing/contrib/libgpg-error-$(GPGERROR_VERSION).tar.bz2