In PhyRegAlloc::saveState(), dump Arguments' saved-state, and try to

make the output more compact.

Divorce state-saving from the doFinalization method; for some reason it's not
getting called when I want it to, at Reoptimizer time. Put the guts in
PhyRegAlloc::finishSavingState(). Put an abort() in it so that I can be really
really sure that it's getting called.

Update comments.

llvm-svn: 12286