keep only the StringRef version of getFileOrSTDIN.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184826 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a typo in the code that collected the costs recursively.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184827 91177308-0d34-0410-b5e6-96231b3b80d8