RFR: 8319716: RISC-V: Add SHA-2 [v7]

[Robbin Ehn]

> Hi, please consider.
> 
> Main author is @luhenry, I only fixed some minor things and tested it.
> 
> Such as:
> test/hotspot/jtreg/compiler/intrinsics/sha/
> test/jdk/java/security/MessageDigest/
> test/jdk/jdk/security/
> tier1
> 
> And still running some test.

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:

 - t2 caller saved, no need to push/pop
 - Merge branch 'master' into sha256
 - Removed swap file
 - Index load, other comment
 - Merge branch 'master' into sha256
 - Materialize constants address once
 - Removed template
 - Flag fixes
 - Merge branch 'master' into sha256
 - Share code
 - ... and 1 more: https://git.openjdk.org/jdk/compare/7132e44a...be46fe4f

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16562/files
  - new: https://git.openjdk.org/jdk/pull/16562/files/c92975e0..be46fe4f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16562&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16562&range=05-06

  Stats: 2823 lines in 219 files changed: 1770 ins; 348 del; 705 mod
  Patch: https://git.openjdk.org/jdk/pull/16562.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16562/head:pull/16562

PR: https://git.openjdk.org/jdk/pull/16562