RFR: JDK-8319958: Fix ifdef to support WIN32 in libGetXSpace.c

[Stewart X Addison]

~~I will force push to change ONLY the commit message once I get a bug created - I am not currently an author. In draft until I do that.~~ Done

FYI @andrew-m-leonard (who I've discussed this with) and @GoeLin

This fixes a build break which has shown up on 32-bit Windows (Deprecated but not removed in [JEP 449](https://openjdk.org/jeps/449)).
Found initially in JDK21, but now also affecting JDK17 where Win32 is still fully supported. I intend to get this into 22 then request a backport to all affected versions. This will need to get in before the January CPU to avoid breaking this platform in the next JDK17 release.

Introduced by https://github.com/openjdk/jdk/commit/3ef834fc6fc245accffc41da714358fc82f22657 under https://github.com/openjdk/jdk/pull/12397 in February
In JDK21: https://github.com/openjdk/jdk21u/commit/3ef834fc6fc245accffc41da714358fc82f22657#diff-6a0b6da94fe13f6caf3b50072a6bef7d559c4b5fc92de7aa2e3c0079f33190d3
That change was backported to JDK17 three weeks ago in https://github.com/openjdk/jdk17u/commit/f85053f578125d1af7c3c762d966fee8283a6ce2

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Commit messages:
 - JDK-8319958: Fix ifdef to support WIN32 in libGetXSpace.c

Changes: https://git.openjdk.org/jdk/pull/16628/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16628&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319958
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16628.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16628/head:pull/16628

PR: https://git.openjdk.org/jdk/pull/16628