Changes since the initial commit:
- Normalize file paths read from the file to prevent Windows path
separators from escaping parts of the path.
- Since we need to store the normalized file paths in WeightedFile,
don't do tricky things to keep the source MemoryBuffer alive.
- Don't use list-initialization for a std::string in WeightedFile.
Differential Revision: http://reviews.llvm.org/D20980
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271953 91177308-0d34-0410-b5e6-96231b3b80d8