create /var/lib/git to improve SELinux compatibility
    
    The README.SELinux file says that the default directory has its context
    set automatically.  This is only true it the cgit package installs the
    directory.  Creating it manually does not result in the proper SELinux
    context being set.
    
    Create and own the directory so that the context is set when the package
    is installed.
    
    This directory is shared with the git-daemon package.  We share
    ownership because cgit is frequently used without git-daemon --
    particularly now that the smart http git protocol is widely deployed.