[Lint] Avoid failed assertion by fetching the proper pointer type

[Lint] Avoid failed assertion by fetching the proper pointer type

Summary:
When checking if a constant expression is a noop cast we fetched the
IntPtrType by doing DL->getIntPtrType(V->getType())). However, there can
be cases where V doesn't return a pointer, and then getIntPtrType()
triggers an assertion.

Now we pass DataLayout to isNoopCast so the method itself can determine
what the IntPtrType is.

Reviewers: arsenm

Reviewed By: arsenm

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D37894

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314763 91177308-0d34-0410-b5e6-96231b3b80d8