Windows 11: Trying to build with `ghc-git-682bf9799b3c3037ee484732bd83c3d21f620fc0`

On Windows 11, trying to build with `compiler: ghc-git-682bf9799b3c3037ee484732bd83c3d21f620fc0` was failing during Stage 1, with:

~~~text
_build/stage0/bin/ghc.exe: createProcess: does not exist (No such file or directory)
~~~

even though `_build/stage0/bin/ghc.exe` had been created during Stage 0.

The reason seems to be a problem with long paths (even though long paths support was enabled). Creating, short, `C:\Temp` and setting `TEMP` and `TMP` to reference it saw GHC built from source.

However, the build has folder `lib\targets` containing file `default.target` and that file has absolute paths. The built GHC does not work, as a consequence.