clang-format: distinguish ObjC call subexpressions after r355434

clang-format: distinguish ObjC call subexpressions after r355434

Summary:
The revision r355434 had the unfortunate side-effect that it started to
recognize certain ObjC expressions with a call subexpression followed by a
`a->b` subexpression as C++ lambda expressions.

This patch adds a bit of logic to handle these cases and documents them in
tests.

The commented-out test cases in the new test suite are ones that were
problematic before r355434.

Reviewers: MyDeveloperDay, gribozavr

Reviewed By: MyDeveloperDay, gribozavr

Subscribers: MyDeveloperDay, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59210

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@355831 91177308-0d34-0410-b5e6-96231b3b80d8