RFR: 8342769: HotSpot Windows/gcc port is broken [v8]

[Julian Waters]

> Several areas in HotSpot are broken in the gcc port. These, with the exception of 1 rather big oversight within SharedRuntime::frem and SharedRuntime::drem, are all minor correctness issues within the code. These mostly can be fixed with simple changes to the code. Note that I am not sure whether the SharedRuntime::frem and SharedRuntime::drem fix is correct. It may be that they can be removed entirely

Julian Waters has updated the pull request incrementally with three additional commits since the last revision:

 - fmod_win64 in sharedRuntime.cpp
 - Should only declare fmod_win64 on Windows/ARM64 sharedRuntime.hpp
 - fmod_win64 in src/hotspot/share/runtime/sharedRuntime.hpp
   
   Co-authored-by: Andrew Haley <aph-open at littlepinkcloud.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21627/files
  - new: https://git.openjdk.org/jdk/pull/21627/files/8f57d674..6caa759b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21627&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21627&range=06-07

  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/21627.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21627/head:pull/21627

PR: https://git.openjdk.org/jdk/pull/21627