Create a kernel-modules-extra subpackage
    
    This creates a modules-extra subpackage which places a number of less
    frequently used modules into the extra directory under
    /lib/modules/`uname -r`/.  This reduces the size of the default kernel
    package while still allowing those modules to be built and installed if
    needed.  We also limit the security exposure by keeping these modules out
    of the default install.