This patch moves convertToUnixPathSeparator from LLD to LLVM.
I'm reluctant to change this type from std::string convert_to_slashes(StringRef) to void convert_to_slashes(SmallVectorImpl<char> &) as the former is easier to use than the latter. In some cases, you can avoid string copy with the latter type, but I think that's very important here. I don't want to optimize unless it is needed.
Sorry for the confusion, I didn't mean to change the signature. By "put the declaration/definition closer" I literally just meant to move the lines of code within the file so that they are nearby.