[clang-format] Keep protobuf "package" statement on one line
Top-level "package" and "import" statements should generally be kept on one
line, for all languages.
Reviewers: sammccall, krasimir, MyDeveloperDay
Reviewed By: MyDeveloperDay
Subscribers: MyDeveloperDay, cfe-commits
Differential Revision: https://reviews.llvm.org/D59627
Patch By: dchai (Donald Chai)