[clang-format] Don't insert space between ObjC class and lightweight generic

Summary:
In D45185, I added clang-format parser support for Objective-C
generics. However, I didn't touch the whitespace logic, so they
got the same space logic as Objective-C protocol lists.

In every example in the Apple SDK and in the documentation,
there is no space between the class name and the opening `<`
for the lightweight generic specification, so this diff
removes the space and updates the tests.

Test Plan: Tests updated. Ran tests with:
  % make -j16 FormatTests && ./tools/clang/unittests/Format/FormatTests

Reviewers: djasper, jolesiak

Reviewed By: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D45498

llvm-svn: 329917