RFR: 8293329: x86: Improve handling of constants in AES/GHASH stubs [v5]

[Vladimir Ivanov]

> Pre-generating constants saves on startup and static/dynamic footprint a bit, plus simplifies bootstrapping logic. 
> 
> As a downside, constants aren't guaranteed to be always reachable anymore, but since they are used from stubs, finding a scratch register when needed is not a problem.
> 
> Testing: 
> - [x] hs-tier1 - hs-tier4 w/ `-XX:+ForceUnreachable` 
> - [x] x86_32 build

Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  fix merge

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10152/files
  - new: https://git.openjdk.org/jdk/pull/10152/files/a603f29e..7b465177

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10152&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10152&range=03-04

  Stats: 7 lines in 1 file changed: 7 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10152.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10152/head:pull/10152

PR: https://git.openjdk.org/jdk/pull/10152