Use FrameIndexTy for stack protector

Using getValueType() is not correct for architectures extended with CHERI since
we need a pointer type and not the value that is loaded. While stack
protector is useless when you have CHERI (since CHERI provides much
stronger security guarantees), we still have a test to check that we can
generate correct code for checks. Merging b281138a1b67ca4405b77d774adc3de72742e7a2
into our tree broke this test. Fix by using TLI.getFrameIndexTy().

Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D77785

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -6360,7 +6360,7 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
 
     int FI = FuncInfo.StaticAllocaMap[Slot];
     MFI.setStackProtectorIndex(FI);
-    EVT PtrTy = Src.getValueType();
+    EVT PtrTy = TLI.getFrameIndexTy(DAG.getDataLayout());
 
     SDValue FIN = DAG.getFrameIndex(FI, PtrTy);