RFR: 8307139: Fix signed integer overflow in compiler code, part 1

[Dean Long]

These changes attempt to fix signed overflow caught by running tier1 with -ftrapv.  I expect more changes will be needed.
Most of the fixes are straight-forward and involve using unsigned or java_* functions that wrap.  However, I did try to improve the usefulness of _debug_idx because as it was the high digits of the value were monotonic but unpredictable.  Now the high digits use the compile_id, which seems like an improvement.

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Commit messages:
 - first pass

Changes: https://git.openjdk.org/jdk/pull/13767/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13767&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307139
  Stats: 66 lines in 21 files changed: 6 ins; 19 del; 41 mod
  Patch: https://git.openjdk.org/jdk/pull/13767.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13767/head:pull/13767

PR: https://git.openjdk.org/jdk/pull/13767