Rename gitweb httpd config file
    
    The gitweb httpd config file was added long before git gained support
    for smart http, in c97cf8e ("Add git-daemon and gitweb packages",
    2007-08-04).
    
    Now, users who want to enable git's smart http support with apache will
    often want to use /etc/httpd/conf.d/git.conf as the path.
    
    Make this easier by giving the gitweb httpd config file a more logical
    name going forward.  Keep the current config file name in previous
    releases.