When linking with X libraries, we need to -R the X library directory
in addition to -Ling it.  autoconf generates code to do this, but only
runs that code on Solaris.

Rather than fixing that, many of our pkgs simply patch Makefile.in to
add the -R option.  This is poor.  The proper answer is to add NetBSD
to the autoconf test in our autoconf pkg, and use patches that update
the generated configure scripts in the relevant pkgs instead.