RFR: 8292352: 32-bit Windows build failures after JDK-8290059

[Aleksey Shipilev]

The affected file was added by [JDK-8290059](https://bugs.openjdk.org/browse/JDK-8290059), and the code that fails the compilation is under `#ifdef _WIN32`, and it only (?) gets compiled for tests. Looks like we really need the "WINAPI" macro in the definition, so that we match the stdcall. See the example declaration in the [docs](https://docs.microsoft.com/en-us/previous-versions/windows/desktop/legacy/ms686736(v=vs.85)).

Attn @JornVernee.

Additional testing:
 - [x] Windows x86_32 builds/test now pass
 - [ ]  Windows x86_64 builds/test still pass

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

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/9875/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9875&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292352
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9875.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9875/head:pull/9875

PR: https://git.openjdk.org/jdk/pull/9875