Remove unused private fields found by clang's new -Wunused-private-field.

There are some that I didn't remove this round because they looked like
obvious stubs. There are dead variables in gtest too, they should be
fixed upstream.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158090 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/SimplifyIndVar.cpp

@@ -16,7 +16,6 @@
 #define DEBUG_TYPE "indvars"
 
 #include "llvm/Instructions.h"
-#include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/IVUsers.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
@@ -44,7 +43,6 @@ namespace {
   class SimplifyIndvar {
     Loop             *L;
     LoopInfo         *LI;
-    DominatorTree    *DT;
     ScalarEvolution  *SE;
     const TargetData *TD; // May be NULL