pthreads.h missing when cross-compiling from OS X to Windows

[jonasteuwen]

In particular, I'm using abseill-cpp, which will assume the existence of pthreads.h

(08:59:11) ERROR: /private/var/tmp/_bazel_jonasteuwen/d145e1e5b1c819e6d5e937b13f41ba9f/external/abseil-cpp~/absl/base/BUILD.bazel:248:11: Compiling absl/base/internal/thread_identity.cc failed: (Exit 1): c++ failed: error executing CppCompile command (from target @@abseil-cpp~//absl/base:base) external/hermetic_cc_toolchain~~toolchains~zig_config/tools/x86_64-windows-gnu/c++ -MD -MF bazel-out/darwin_arm64-opt/bin/external/abseil-cpp~/absl/base/_objs/base/thread_identity.d ... (remaining 57 arguments skipped)

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
external/abseil-cpp~/absl/base/internal/thread_identity.cc:18:10: fatal error: 'pthread.h' file not found
   18 | #include <pthread.h>
      |          ^~~~~~~~~~~
1 error generated.

This seems to be related to ziglang/zig#10989, where they seem to have solved the problem. I see that ziglang/zig#22156 apparently would solve it.

However, that doesn't seem to be exposed in hermetic_cc_toolchain. Any known workarounds?