Reorder VFPU registers in memory so that we can flush and reload them in bulk more often.

Doesn't actually do that yet, that's for the NEON branch.
Reorder vfpu data in saved kernel contexts when loading in a new version.
Fix some bugs. Inexplicably still broken in jit.
Fix wrong bugfix, add a comment.
Extend sanity check for vfpu reordering array.