Log Message:
Do not assume that if /usr/lib/libintl.* does not exist
that it can not be builtin.  So also check for "This file is part
of the GNU C Library".

This helps with systems that have gettext(3) functionality
included in their glibc.

This also fixes build problem under Linux where devel/popt didn't
build "because some functions are defined both in gettext-lib and
in the native libc" as reported by minskim to tech-pkg on 21/Mar/2004.