Previous changes enabled gzip compressed Linux kernels, but not 100%
sure that it works on all systems. Disable this compression for now.
Switch hppa to use xorriso by default instead of mkisofs. Xorriso
supports kernel command lines to be up to 1023 bytes, better than
mkisofs. mkisofs only supports the older palo version 4 header format
which can hold only 127 characters which might be too small.
Steve McIntyre