There is a new pull request by xtraeme against master on the void-packages repository

https://github.com/xtraeme/void-packages mingw-musl
https://github.com/void-linux/void-packages/pull/12332

cross-x86_64-w64-mingw32: allow building on musl.
Successfully built it on x86_64-musl:

index: added `cross-i686-w64-mingw32-6.0.0_1' (x86_64-musl).
index: added `cross-i686-w64-mingw32-crt-6.0.0_1' (x86_64-musl).
index: added `cross-x86_64-w64-mingw32-6.0.0_1' (x86_64-musl).
index: added `cross-x86_64-w64-mingw32-crt-6.0.0_1' (x86_64-musl).
index: 17 packages registered.

Signed-off-by: Juan RP <xtraeme@gmail.com>

A patch file from https://github.com/void-linux/void-packages/pull/12332.patch is attached