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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@293604 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 760abb81d09f254e45152609644192607c10107a)
2 files changed