RFR: 8308975: Fix signed integer overflow in compiler code, part 2

[Dean Long]

This is a followup from part 1.  I had to use java_add/subtract/multiply/negate in a few more places.
cpu_loads_process had an overflow on BSD when the first snapshot is relative to the epoch in 1970.
Use unsigned for C2 Type hash functions.

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Commit messages:
 - part 2

Changes: https://git.openjdk.org/jdk/pull/14188/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14188&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308975
  Stats: 89 lines in 9 files changed: 7 ins; 7 del; 75 mod
  Patch: https://git.openjdk.org/jdk/pull/14188.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14188/head:pull/14188

PR: https://git.openjdk.org/jdk/pull/14188