[Format/ObjC] Avoid breaking between unary operators and operands

Summary:
Test Plan:
  New tests added. Ran tests with:
  % ninja FormatTests && ./tools/clang/unittests/Format/FormatTests
  Confirmed tests failed before change and passed after change.

Reviewers: krasimir, djasper, sammccall, klimek

Reviewed By: sammccall

Subscribers: klimek, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64775

llvm-svn: 366592