contribs: move OpenJPEG downloads to github releases

After complete migration to github
http://www.openjpeg.org/2015/07/19/github-migration-and-new-website
the old download links do not work.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/openjpeg/SHA512SUMS

-59501fde86a7f0ab5a1b7e369feb9c4dcb8ea67ead8ffd706592cbba1e0ee7b2a2a9aaa32778632febe0c3dc4171c7af738c5899c732eb420358df3b16d7cf47  openjpeg-1.5.0.tar.gz
+dca4f3006119673e3c0ef68f2847bb67bf5a406caf30bf7f2e08904eff013f79af9302e25fc6077cb593b80760deb324dfb9326b40ccc172401ae7dd91b9db20  openjpeg-version.1.5.tar.gz

contrib/src/openjpeg/rules.mak

 # jpeg
 
-OPENJPEG_VERSION := 1.5.0
-OPENJPEG_URL := http://openjpeg.googlecode.com/files/openjpeg-$(OPENJPEG_VERSION).tar.gz
+OPENJPEG_VERSION := version.1.5
+OPENJPEG_URL := https://github.com/uclouvain/openjpeg/archive/$(OPENJPEG_VERSION).tar.gz
 
 $(TARBALLS)/openjpeg-$(OPENJPEG_VERSION).tar.gz:
 	$(call download_pkg,$(OPENJPEG_URL),openjpeg)