Log Message:
Disable -Werror to avoid build failures.

At least on OS X with clang, pkgin fails to build because of extra
parens around ==.  See https://github.com/NetBSDfr/pkgin/issues/64
for details.

This seems to be a new issue with something in the pkgsrc build
environment (bsd makefiles or compat libs), not in pkgin proper, but
pkgin's use of bsd makefiles leads to Werror.