[llvm] [lit] Echo full RUN lines in case of external shells (PR #66408)

[Joel E. Denny via llvm-commits]

jdenny-ornl wrote:

> Thanks for telling me how to, it is much more useful now!

Great!

> > > ```
> > >          8: bash.exe: warning: could not find /tmp, please create! 
> > > ```
> > 
> > 
> > Do you know why this is being printed at all? Is it reasonable to just create that directory on that bot?
> 
> I could, although I vaguely recall having similar problems in the past trying to get rid of this error, but I can try. I would prefer that the test can handle it just in case though.

Understood.

> > > Can the test be restructured such that it can handle this?
> > 
> > 
> > I'm concerned about weakening the test and missing other problems. I might use `grep -v` to throw away that line. Is that portable to windows?
> 
> I'm not sure. I think there are some tests that still do use grep, but I think the usage of it is highly discouraged these days.

I grepped for grep and found a number of tests still using it.  I'll push a commit with this solution for now so that (hopefully) the bot is green again.  We can try to find a better solution afterward.  Does that seem reasonable?

https://github.com/llvm/llvm-project/pull/66408