Integrity check for compressed /dev/map/cfg

[Eugene Grosbein]

Hi!

While preparing my FreeBSD/mips system, I have to check if /dev/map/cfg contains
garbage or stored data. I've found a bug in our gzip(1) utility: it returns same
exit code (1) for unrecognized or corrupted data and for correct data having trailing garbage.
Meantime, GNU gzip returns exit code 2 when data is correct but has trailing garbage.

I've prepared trivial one-line patch for our gzip so it returns 2 in such case
making it more compatible with GNU gzip and more embedded friendly :-)

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203873