[CK][Windows]: fmha_fwd_head_grouping guard posix headers and use of posix only functions on Windows

[astrelsky]

Motivation

The purpose is to fix the build errors when compiling for Windows when fmha_fwd_head_grouping.hpp is included.

Technical Details

This checks if _WIN32 is defined and prevents including posix headers and use of posix functions. There is currently no way to get the L3 cache size. If the architecture is not one of the ones currently hardcoded with the L3 cache size, it will return the default error value.

Test Plan

Tested locally building flash-attention with CK on Windows. (See comments here Dao-AILab/flash-attention#2400 (comment))

Test Result

Builds successfully only when using setuptools that include the distutils patch here pypa/distutils#406

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

@Snektron @0xDELUXA

[0xDELUXA]

Looking forward to this being merged, as CK is supported on Windows, but this PR introduced Linux-only components. Applying the changes from this PR on Windows is necessary to maintain compatibility.

[brockhargreaves-amd]

Duplicate of #5977

[0xDELUXA]

Duplicate of #5977

Sorry, we didn’t notice #5977.

[astrelsky]

Duplicate of #5977

Yup I didn't notice it.

[brockhargreaves-amd]

Duplicate of #5977

Sorry, we didn’t notice #5977.

No worries, thank you for the contribution none the less!