GitLab

* replace links to several years old versions with installation commands
  for various distros
* mention pkgconf in both INSTALL and README.md (many distros migrated
  from pkg-config to pkgconf)
* remove make version requirement (make 3.81 is in CentOS 6, which
  support were going to drop)
* remove CVS tag :)
Reviewed-by: Li Wang <liwang@redhat.com>
Acked-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>