On Windows it's possible to build VLC in either msys2 or WSL. But the tools are
shared and incompatible. Only one at a time is currently possible. This will
allow switching back and forth without rebuilding tools all the time
(especially since they are detected as built).

(cherry picked from commit 85d46570)
Signed-off-by: Steve Lhomme <robux4@ycbcr.xyz>