More mips support code committed

This weekend, I've committed more mips support code. Everything except for the tool chain is now in the tree. The tool chain will be pushed in over the next week or so. I have to verify that some changes I remember having to make to the tool chain are compatible with the tool chain that's in the FreeBSD repository. When everything has been pushed into the tree, I'll enable it as part of the make universe target.

FreeBSD/mips is starting to get attention from other FreeBSD developers now that it is in the tree. Alan Cox has started to audit the Mips pmap, for example. This should help FreeBSD/mips transition to the next level of support.

Many changes are still needed for the mips port. We need to audit the basic libc functions to make sure that we haven't stubbed anything out that's going to bite us in the future. We need to look to see if there's anything that can be refactored from the 3 different embedded platforms in the tree today (powerpc, arm and mips). Better documentation and porting to new chips/boards would help us to make things more portable.