Re-enable the IdempotentOperations checker for --analyze, and put it and the DeadStores checker into the "deadcode" group.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127531 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 68439ce..271f02d 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1011,7 +1011,8 @@
       if (getToolChain().getTriple().getVendor() == llvm::Triple::Apple)
         CmdArgs.push_back("-analyzer-checker=macosx");
 
-      CmdArgs.push_back("-analyzer-checker=DeadStores");
+      CmdArgs.push_back("-analyzer-checker=deadcode.DeadStores");
+      CmdArgs.push_back("-analyzer-checker=deadcode.IdempotentOperations");
 
       // Checks to perform for Objective-C/Objective-C++.
       if (types::isObjC(InputType)) {