RFR: 8296168: x86: Add reasonable constraints between AVX and SSE [v2]

[Claes Redestad]

> We've not seen any x86 CPU, Intel or otherwise, where AVX features are available but SSE 4.1 is not supported. This patch suggests constraining setup so that any explicit value of UseSSE less than 4 (the default on any AVX-supporting CPU) implicitly disables AVX. This simplifies ergonomics and reduces the testing surface. Concretely this would allow #10847 to not have to guard the new intrinsic on UseSSE level to avoid some surprising test failures in tests verifying SSE-enabled intrinsics.
> 
> I've rearranged the initialization of UseAVX and UseSSE to allow AVX to look at the post-ergo values of UseSSE.
> 
> Testing: tier1-tier3, manual verification

Claes Redestad has updated the pull request incrementally with two additional commits since the last revision:

 - Remove redundant SSE < 0 check
 - Remove redundant AVX < 0 check, revert narrow supports_sse4_1 check

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10946/files
  - new: https://git.openjdk.org/jdk/pull/10946/files/b3d347c8..4c2e9ca5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10946&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10946&range=00-01

  Stats: 7 lines in 1 file changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10946.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10946/head:pull/10946

PR: https://git.openjdk.org/jdk/pull/10946