Don't use PathV1.h in LTOCodeGenerator.cpp

This patch also adds a simpler version of sys::fs::remove and a tool_output_file
constructor for when we already have an open file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184095 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/FileSystem.h

@@ -292,6 +292,13 @@ error_code current_path(SmallVectorImpl<char> &result);
 ///          successfully set, otherwise a platform specific error_code.
 error_code remove(const Twine &path, bool &existed);
 
+/// @brief Convenience function for clients that don't need to know if the file
+///        existed or not.
+inline error_code remove(const Twine &Path) {
+  bool Existed;
+  return remove(Path, Existed);
+}
+
 /// @brief Recursively remove all files below \a path, then \a path. Files are
 ///        removed as if by POSIX remove().
 ///