Remove custom FreeBSD compiler flags that are only supported by our old base GCC 4.2

- Remove ancient library paths
- Add missing includes that our base gcc did not need

This gives us proper support for newer GCC 4.6 from ports.

Submitted by:	Andriy Gapon <avg@FreeBSD.org>
Merge branch 'master' of https://github.com/decke/freebsd-vbox