Commit 82b47b2978405f802a33b00d046e6f18ef6a47be changes the way the stdlib.h header is structured which seems to cause strange lookup failures in the modules build. This updates a few failing tests so that they pass with the new behavior of stdlib.h. See the discussion in https://reviews.llvm.org/rG82b47b2978405f802a33b00d046e6f18ef6a47be