NNT: Use [e]grep -a when scanning logs, its possibly they will have non-text

NNT: Use [e]grep -a when scanning logs, its possibly they will have non-text
characters in them, in which case the grep will just return 'Binary file
matches' and the whole thing falls over.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91302 91177308-0d34-0410-b5e6-96231b3b80d8