Backport %gpgverify API simplification
Allow EPEL packages to use the simpler %gpgverify API which is available
in Fedora. This incorporates the changes made to redhat-rpm-config in
the following commits:
3490049 (Simplify the API of %gpgverify, 2019-07-25)
4d93255 (Fix the simple API of %gpgverify, 2019-11-01)