"sendmsg6: rewrite IP & port (C)" fails on s390, because the code in
sendmsg_v6_prog() assumes that (ctx->user_ip6[0] & 0xFFFF) refers to
leading IPv6 address digits, which is not the case on big-endian
machines.
Since checking bitwise operations doesn't seem to be the point of the
test, replace two short comparisons with a single int comparison.