[InstCombine] add helper to foldXorOfICmps(); NFCI

Also, fix the old-style capitalization of the related functions
and move them to the 'private' section of the class since they
are just helpers of the visit* functions.

As shown in the post-commit comments for D32143, we are missing
folds for xor-of-icmps. 

llvm-svn: 303381
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index f88a2c6..4b683cb 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -275,11 +275,7 @@
   Instruction *visitSDiv(BinaryOperator &I);
   Instruction *visitFDiv(BinaryOperator &I);
   Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted);
-  Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
-  Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
   Instruction *visitAnd(BinaryOperator &I);
-  Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI);
-  Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
   Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A,
                                    Value *B, Value *C);
   Instruction *FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A,
@@ -445,6 +441,12 @@
   Instruction::CastOps isEliminableCastPair(const CastInst *CI1,
                                             const CastInst *CI2);
 
+  Value *foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
+  Value *foldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
+  Value *foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI);
+  Value *foldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
+  Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS);
+
 public:
   /// \brief Inserts an instruction \p New before instruction \p Old
   ///