RFR: 8310906: Fix -Wconversion warnings in runtime, oops and some code header files.

[Coleen Phillimore]

More casts for size of address differences in same code space, checked_casts<> and type changes to fix -Wconversion warnings.  See CR for details.
Tested with tier1-4.

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Commit messages:
 - Fix -Wconversion warnings in runtime, oops and some code header files.

Changes: https://git.openjdk.org/jdk/pull/14659/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14659&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310906
  Stats: 71 lines in 36 files changed: 0 ins; 0 del; 71 mod
  Patch: https://git.openjdk.org/jdk/pull/14659.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14659/head:pull/14659

PR: https://git.openjdk.org/jdk/pull/14659