Use llvm::DeleteContainerSeconds when possible

llvm-svn: 201739
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index dd650ae..e2ff568 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -77,10 +77,7 @@
 Driver::~Driver() {
   delete Opts;
 
-  for (llvm::StringMap<ToolChain *>::iterator I = ToolChains.begin(),
-                                              E = ToolChains.end();
-       I != E; ++I)
-    delete I->second;
+  llvm::DeleteContainerSeconds(ToolChains);
 }
 
 void Driver::ParseDriverMode(ArrayRef<const char *> Args) {