[globalisel][tablegen] Finish fixing compile-time regressions by merging the matcher...

[globalisel][tablegen] Finish fixing compile-time regressions by merging the matcher and emitter state machines.

Summary:
Also, made a few minor tweaks to shave off a little more cumulative memory consumption:
* All rules share a single NewMIs instead of constructing their own. Only one
  will end up using it.
* Use MIs.resize(1) instead of MIs.clear();MIs.push_back(I) and prevent
  GIM_RecordInsn from changing MIs[0].

Depends on D33764

Reviewers: rovka, vitalybuka, ab, t.p.northover, qcolombet, aditya_nandakumar

Reviewed By: ab

Subscribers: kristof.beyls, igorb, llvm-commits

Differential Revision: https://reviews.llvm.org/D33766

llvm-svn: 307159