Require annobin only if gcc is installed
Since b5ea4b290b4eace5568bb1a9a3fe178faae1c2d1 we started to require gcc
(because annobin requires gcc). Since annobin does work only with gcc,
we don't have to install it if user doesn't have it.
Reported-by: Dominick Grift <dac.override@gmail.com>
Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>