Log Message:
Fix:
cannot create /bin/msgfmt: read-only file system
cannot create /bin/msgfmt: read-only file system
chmod: /bin/msgfmt: No such file or directory

Solution:
Do not include gettext-lib/builtin.mk, if it's included
to early, BUILDLINK_DIR is not defined. Use gettext-lib/buildlink3.mk
instead.

While here, remove superfluous inclusion of bsd.prefs.mk.