Replace all uses of PathV1::isAbsolute with PathV2::is_{absolute,relative}.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122087 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/FileManager.cpp b/lib/Basic/FileManager.cpp
index 488d4c3..921778d 100644
--- a/lib/Basic/FileManager.cpp
+++ b/lib/Basic/FileManager.cpp
@@ -392,10 +392,11 @@
 
 void FileManager::FixupRelativePath(llvm::sys::Path &path,
                                     const FileSystemOptions &FSOpts) {
-  if (FSOpts.WorkingDir.empty() || path.isAbsolute()) return;
-  
-  llvm::sys::Path NewPath(FSOpts.WorkingDir);
-  NewPath.appendComponent(path.str());
+  if (FSOpts.WorkingDir.empty() || llvm::sys::path::is_absolute(path.str()))
+    return;
+
+  llvm::SmallString<128> NewPath(FSOpts.WorkingDir);
+  llvm::sys::path::append(NewPath, path.str());
   path = NewPath;
 }