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
diff --git a/tools/llvm-diff/DifferenceEngine.h b/tools/llvm-diff/DifferenceEngine.h
index 7ea79e4..0246d8f 100644
--- a/tools/llvm-diff/DifferenceEngine.h
+++ b/tools/llvm-diff/DifferenceEngine.h
@@ -59,8 +59,8 @@
       virtual ~Oracle() {}
     };
 
-    DifferenceEngine(LLVMContext &context, Consumer &consumer)
-      : context(context), consumer(consumer), globalValueOracle(0) {}
+    DifferenceEngine(Consumer &consumer)
+      : consumer(consumer), globalValueOracle(0) {}
 
     void diff(Module *L, Module *R);
     void diff(Function *L, Function *R);
@@ -84,7 +84,6 @@
     bool equivalentAsOperands(GlobalValue *L, GlobalValue *R);
 
   private:
-    LLVMContext &context;
     Consumer &consumer;
     Oracle *globalValueOracle;
   };