There are two issues here:
1) It's too late to rebuild at this point, because we won't go through
removeModules and when we try to reload the new .pcm we'll get the old
one instead. We might be able to call removeModules after an OutOfDate
here, but I'm not yet confident that it is always safe to do so.
2) In practice, this check fails spuriously when the umbrella header
appears to change because of a VFS change that means it maps to a
different copy of the same file. Because of this, we just skip the
check for now.
llvm-svn: 230064
Richard Smith