There is a new pull request by svlobanov against master on the mblaze repository

https://github.com/svlobanov/mblaze allow-override-OS
https://github.com/leahneukirchen/mblaze/pull/220

allow to override Makefile OS variable
Overriding OS is useful for cross-compiling if build OS and
target OS are different (e.g. build on MacOS for Linux)

Signed-off-by: Sergey V. Lobanov <sergey@lobanov.in>

A patch file from https://github.com/leahneukirchen/mblaze/pull/220.patch is attached