[clang-format] Refine structured binding detection
Summary:
Revision r356575 had the unfortunate consequence that now clang-format never
detects an ObjC call expression after &&.
This patch tries harder to distinguish between C++17 structured bindings and
ObjC call expressions and adds a few regression tests.
Reviewers: klimek
Reviewed By: klimek
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59774
llvm-svn: 356928