This patch adds useflag support to freebsd-lib, allowing to remove a lot of stuff, for example also kerberos support can be disabled, and also can bind, sendmail and ssl related stuff. The patch also remove the virtual/glibc provide, as the libc provided by this package is not fully glibc-compatible. As for freebsd-ubin, there's here a patch which disable com_err compilation (which were needed only for kerberos stuff, anyway), which as seemant said is going to be done in a standalone ebuild (which will be a dependency of this package as soon as it will be done; until that, kerberos stuff is b0rken).
Created attachment 53620 [details, diff] Patch for freebsd-lib
Argh. I'll take care of this one later.
It's in cvs now, although not yet fully tested (I need to reinstall my g/fbsd system, since it's a bit messy).