Add myself as the code owner for a bunch of stuff.

Add myself as the code owner for a bunch of stuff.

Notably, I'm reviewing this stuff already, and this makes it clear I'm
on the hook for it.

I'm relying on Eric Christopher and Michael Spencer to help with Support
when there are platform specific issues, but Chris wants a single point
of contact, and I'm happy with that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168164 91177308-0d34-0410-b5e6-96231b3b80d8