media-fonts/cantarell: requires appstream

Also, drop keywords that appstream doesn't have.

Closes: https://bugs.gentoo.org/656710
Closes: gentoo#9115

media-fonts/cantarell/cantarell-0.101.ebuild

@@ -11,11 +11,12 @@ HOMEPAGE="https://wiki.gnome.org/Projects/CantarellFonts"
 
 LICENSE="OFL-1.1"
 SLOT="0"
-KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~mips ~ppc ~ppc64 ~s390 ~sh ~sparc ~x86 ~x86-fbsd"
+KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~mips ~sh ~sparc ~x86 ~x86-fbsd"
 IUSE=""
 
 RDEPEND="media-libs/fontconfig"
 DEPEND="
+ dev-libs/appstream
  >=sys-devel/gettext-0.19.8
  virtual/pkgconfig
 "