std.Build.Step.Run: global lock when child inherits stderr
The docs for setting stdio to "inherit" say:
It also means that this step will obtain a global lock to prevent other
steps from running in the meantime.
The implementation of this lock was missing but is now provided by this
commit.
closes #20119
4918c2ce2dAndrew Kelley committed on 5/31/2024, 10:59:53 PMparentc564a16