fix Sema/unused-expr.c failing on r39999

Clang Frontend
#1

I needed the following patch so that test/Sema/unused-expr.c does not
fail:

#2

Thanks for the (timely) patch (I planned on fixing this today:-).

snaroff

#3

I needed the following patch so that test/Sema/unused-expr.c does not
fail:

Applied, thanks! With future patches, please include them as attachments to the email. This one applied fine, but I've had trouble with inline attachments in the past.

Thanks again,

-Chris