[Frontend] Close open file handles before renaming output files

The placement of the 'delete' call that was removed in the unique_ptr
migration in r234597 was not an accident. The raw_ostream has to be
destroyed before you do the rename on Windows, otherwise you get
ERROR_ACCESS_DENIED. We can still use unique_ptr, we just need to do a
manual reset().

Also, range-for-loop-ify this code.

llvm-svn: 234612
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 5bb7f15..0628442 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -524,27 +524,29 @@
 }
 
 void CompilerInstance::clearOutputFiles(bool EraseFiles) {
-  for (std::list<OutputFile>::iterator
-         it = OutputFiles.begin(), ie = OutputFiles.end(); it != ie; ++it) {
-    if (!it->TempFilename.empty()) {
+  for (OutputFile &OF : OutputFiles) {
+    // Manually close the stream before we rename it.
+    OF.OS.reset();
+
+    if (!OF.TempFilename.empty()) {
       if (EraseFiles) {
-        llvm::sys::fs::remove(it->TempFilename);
+        llvm::sys::fs::remove(OF.TempFilename);
       } else {
-        SmallString<128> NewOutFile(it->Filename);
+        SmallString<128> NewOutFile(OF.Filename);
 
         // If '-working-directory' was passed, the output filename should be
         // relative to that.
         FileMgr->FixupRelativePath(NewOutFile);
         if (std::error_code ec =
-                llvm::sys::fs::rename(it->TempFilename, NewOutFile)) {
+                llvm::sys::fs::rename(OF.TempFilename, NewOutFile)) {
           getDiagnostics().Report(diag::err_unable_to_rename_temp)
-            << it->TempFilename << it->Filename << ec.message();
+            << OF.TempFilename << OF.Filename << ec.message();
 
-          llvm::sys::fs::remove(it->TempFilename);
+          llvm::sys::fs::remove(OF.TempFilename);
         }
       }
-    } else if (!it->Filename.empty() && EraseFiles)
-      llvm::sys::fs::remove(it->Filename);
+    } else if (!OF.Filename.empty() && EraseFiles)
+      llvm::sys::fs::remove(OF.Filename);
 
   }
   OutputFiles.clear();