modularity: drop '*-libs' and '*-devel' subpackages
    
    The PostgreSQL shared libraries are moved to 'libpq' and 'libecpg'
    packages, which allows us to have single library version per
    Fedora release, even though we will provide multiple versions of
    PostgreSQL servers.
    
    Related: rhbz#1618698
    Version: 10.5-4