[analyzer] Do not assert on reports ending in calls within macros.

The crash is triggered by the newly added option (-analyzer-config report-in-main-source-file=true) introduced in r182058.

Note, ideally, we’d like to report the issue within the main source file here as well.
For now, just do not crash.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182445 91177308-0d34-0410-b5e6-96231b3b80d8