Reimplements fastmem for ARMv7 floating point loadstores.

This implements a new system for fastmem backpatching on ARMv7 that is less of a mindfsck to deal with.
This also implements stfs under the default loadstore path as well, not sure why it was by itself in the first place.

I'll be moving the rest of the loadstore methods over to this new way in a few days.