Fix an issue in the verifier where we could try to read information out of a malforme...

Fix an issue in the verifier where we could try to read information out of a malformed statepoint intrinsic.

In this situation we would always have already flagged an error on the statepoint intrinsic,
but then we carry on to parse other, related GC intrinsics, and could end up crashing during that
verification when they try to access data from the malformed statepoint.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231759 91177308-0d34-0410-b5e6-96231b3b80d8