[clang-format] Break template declarations followed by comments

Summary:
This patch fixes two bugs in clang-format where the template wrapper doesn't skip over
comments causing a long template declaration to not be split into multiple lines.
These were latent and exposed by r332436.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D47257

llvm-svn: 333085