maint: update PKG_UPDATE targets * src/boost.mk: update UPDATE target, use https * src/cmake.mk: add usable UPDATE target * src/double-conversion.mk: add usable UPDATE target * src/dri2proto.mk: add PKG_UPDATE * src/exiv2.mk: update UPDATE for archives * src/fribidi.mk: update UPDATE for github * src/glproto.mk: add PKG_UPDATE * src/glu.mk: add PKG_UPDATE * src/levmar.mk: add user-agent to UPDATE * src/libarchive.mk: update UPDATE for website * src/libass.mk: update UPDATE for github * src/libdrm.mk: add PKG_UPDATE * src/libffi.mk: update for webpage changes * src/libgee.mk: update for gnome page changes * src/libgsf.mk: update for gnome page changes * src/libidn2.mk: correct PKG_UPDATE

--- a/src/libass.mk	Fri Nov 17 12:55:19 2017 -0500
+++ b/src/libass.mk	Tue Nov 21 12:03:47 2017 -0500
@@ -11,9 +11,9 @@
 $(PKG)_DEPS     := freetype fontconfig fribidi
 
 define $(PKG)_UPDATE
-    $(WGET) -q -O- 'http://code.google.com/p/libass/downloads/list?sort=-uploaded' | \
-    $(SED) -n 's,.*libass-\([0-9][^<]*\)\.tar.*,\1,p' | \
-    head -1
+    $(WGET) -q -O- 'https://github.com/libass/libass/tags' | \
+    $(SED) -n 's|.*releases/tag/\([^"]*\).*|\1|p' | $(SORT) -V | \
+    tail -1
 endef
 
 define $(PKG)_BUILD