Fix Win32 Path.inc for API update.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91706 91177308-0d34-0410-b5e6-96231b3b80d8

lib/System/Win32/Path.inc

@@ -47,7 +47,7 @@ namespace llvm {
 namespace sys {
 const char PathSeparator = ';';
 
-Path::Path(const std::string& p)
+Path::Path(llvm::StringRef p)
   : path(p) {
   FlipBackSlashes(path);
 }