libtirpc: added version 0.2.2

The glibc maintainers in their wisdom have dropped RPC support. That change
causes plenty of builds to fail, like PAM. Users are supposed to use libtirpc
instead, which, naturally, doesn't compile with glibc 2.14. I'm adding the
library anyway, just so that we have it.

svn path=/nixpkgs/branches/stdenv-updates/; revision=30029