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

[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

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Depends on: https://git.openjdk.org/jdk/pull/10124

Commit messages:
 - constants

Changes: https://git.openjdk.org/jdk/pull/10152/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10152&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293329
  Stats: 502 lines in 6 files changed: 152 ins; 227 del; 123 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