[CodeComplete] Add a trailing semicolons to some pattern completions

Summary:
Where semicolon is required in any case. Here's a list of completions
that now have a semicolon:
  - namespace <name> = <target>;
  - using namespace <name>;
  - using <qualifier>::<name>;
  - continue;
  - break;
  - goto <label>;
  - return;
  - return <expression>;

Reviewers: gribozavr

Reviewed By: gribozavr

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61589

llvm-svn: 360042