Update GeoIP country code list
prevent country/continent-table overflows
Fixup invalid memcmp() semantics on labels/dnames

Technically this doesn't cause real problems, but that's
a combination of typical memcmp/malloc implementation details
and our internal data formats (len byte first), neither of which
may be wholly reliable in some esoteric cases.  With this patch,
we no longer ask memcmp to potentially read uninitialized/invalid
memory in these cases, which gets rid of our only known violations
of strict_memcmp with -faddress-sanitizer.