RFR: 8319822: Use a linear-time algorithm for assert_different_registers() [v8]

[Andrew Haley]

> At the present time, `assert_different_registers()` uses an O(N**2) algorithm in assert_different_registers(). We can utilize RegSet to do it in O(N) time. This would be a useful optimization for all builds with assertions enabled.
> 
> In addition, it would be useful to be able to static_assert different registers. 
> 
> Also, I've taken the opportunity to expand the maximum size of a RegSet to 64 on 64-bit platforms.
> 
> I also fixed a bug: sometimes `noreg` is passed to `assert_different_registers()`, but it may only be passed once or a spurious assertion is triggered.

Andrew Haley 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 13 additional commits since the last revision:

 - Review feedback
 - Merge branch 'different-regs' of https://github.com/theRealAph/jdk into different-regs
 - Update src/hotspot/share/asm/register.hpp
   
   Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
 - Merge branch 'clean' into different-regs
 - Review feedback.
 - 8319822: Use a linear-time algorithm for assert_different_registers()
 - 8319822: Use a linear-time algorithm for assert_different_registers()
 - Cleanup, fix warning on Windows.
 - Fix x86
 - Bleurgh
 - ... and 3 more: https://git.openjdk.org/jdk/compare/211fe58c...0037dd29

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16617/files
  - new: https://git.openjdk.org/jdk/pull/16617/files/36f48ad0..0037dd29

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16617&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16617&range=06-07

  Stats: 1504428 lines in 12564 files changed: 341226 ins; 719204 del; 443998 mod
  Patch: https://git.openjdk.org/jdk/pull/16617.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16617/head:pull/16617

PR: https://git.openjdk.org/jdk/pull/16617