Summary:
This reverts commit r328596.
Checking if the arguments are strings before testing if they contain "/dev/null".
Reviewers: rnk
Reviewed By: rnk
Subscribers: delcypher, llvm-commits
Differential Revision: https://reviews.llvm.org/D44914
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328603 91177308-0d34-0410-b5e6-96231b3b80d8