Improvements in the Inliner.

- Change from a depth limit to a total number of HInstructions
  inlined limit. Remove the dex2oat depth limit argument.
- Add more stats to diagnose reasons for not inlining.
- Clean up logging to easily parse output.

Individual Ritz benchmarks improve from 3 to 10%.

No change in other heuristics. There was already an instruction budget.
Note that the instruction budget is rarely hit in the "apps" I've tried
with.

Compile-times improve from 5 to 15%.
Code size go from 4% increase (Gms) to 1% decrease (Docs).

bug:35724239
test: test-art-host test-art-target

Change-Id: I5a35c4bd826cf21fead77859709553c5b57608d6