RFR: 8310906: Fix -Wconversion warnings in runtime, oops and some code header files. [v4]

[Coleen Phillimore]

> This is another version of PR https://github.com/openjdk/jdk/pull/14659 but I've added a pointer delta function in globalDefinitions.hpp to use for these pointer diff calculations that return int everywhere.  If the name is agreeable, I'll fix the other cases of this like this.  It's better than raw casts.
> Tested with tier1-4.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Use pointer_delta_as_int for the name that uses pointer_delta, fix negative case to just do checked_cast.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14675/files
  - new: https://git.openjdk.org/jdk/pull/14675/files/858e9cfb..9fed8c89

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14675&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14675&range=02-03

  Stats: 22 lines in 14 files changed: 0 ins; 1 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/14675.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14675/head:pull/14675

PR: https://git.openjdk.org/jdk/pull/14675