[analyzer] Guard against C++ member functions that look like system functions.

C++ method calls and C function calls both appear as CallExprs in the AST.
This was causing crashes for an object that had a 'free' method.

<rdar://problem/11822244>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160029 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed