RFR: JDK-8241503: C2: Share MacroAssembler between mach nodes during code emission [v11]

[Cesar Soares Lucas]

> # Description
> 
> Please review this PR with a patch to re-use the same C2_MacroAssembler object to emit all instructions in the same compilation unit.
> 
> Overall, the change is pretty simple. However, due to the renaming of the variable to access C2_MacroAssembler, from `_masm.` to `masm->`, and also some method prototype changes, the patch became quite large.
> 
> # Help Needed for Testing
> 
> I don't have access to all platforms necessary to test this. I hope some other folks can help with testing on `S390`, `RISC-V` and `PPC`.

Cesar Soares Lucas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:

 - Merge remote-tracking branch 'origin/master' into reuse-macroasm
 - Fix AArch64 build & improve comment about InstructionMark
 - Catching up with changes in master
 - Catching up with origin/master
 - Catch up with origin/master
 - Merge with origin/master
 - Fix build, copyright dates, m4 files.
 - Fix merge
 - Catch up with master branch.
   
   Merge remote-tracking branch 'origin/master' into reuse-macroasm
 - Some inst_mark fixes; Catch up with master.
 - ... and 2 more: https://git.openjdk.org/jdk/compare/89e0889a...b4d73c98

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Changes: https://git.openjdk.org/jdk/pull/16484/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16484&range=10
  Stats: 2153 lines in 60 files changed: 136 ins; 431 del; 1586 mod
  Patch: https://git.openjdk.org/jdk/pull/16484.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16484/head:pull/16484

PR: https://git.openjdk.org/jdk/pull/16484