Merging r293604:

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r293604 | sammccall | 2017-01-30 21:23:20 -0800 (Mon, 30 Jan 2017) | 12 lines

In VirtualCallChecker, handle indirect calls

Summary:
In VirtualCallChecker, handle indirect calls.

getDirectCallee() can be nullptr, and dyn_cast(nullptr) is UB

Reviewers: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D29303
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llvm-svn: 296154