[IR] Use UnaryOperator::CreateFNeg in NoFolder::createFNeg

[craig.topper]

Summary

If IRBuilder is constructed using the NoFolder constant folder, we should use the Unary FNeg to match the non-constant part of IRBuilder.

[cameron.mcinally]

Good catch. Thanks. LGTM.

I'll volunteer to handle any regressions that result from this change...

llvm/include/llvm/IR/NoFolder.h

Instruction *CreateNSWNeg(Constant *C) const {
     return BinaryOperator::CreateNSWNeg(C);
   }
 
   Instruction *CreateNUWNeg(Constant *C) const {
     return BinaryOperator::CreateNUWNeg(C);
   }
 
   Instruction *CreateFNeg(Constant *C) const {
-    return BinaryOperator::CreateFNeg(C);
+    return UnaryOperator::CreateFNeg(C);
   }
 
   Instruction *CreateNot(Constant *C) const {
     return BinaryOperator::CreateNot(C);
   }
 
   Instruction *CreateUnOp(Instruction::UnaryOps Opc, Constant *C) const {
     return UnaryOperator::Create(Opc, C);