clang-format: [Java] Improve formatting of throws declarations.

Before:
  public void doSoooooooooo() throws LoooooooooongException,
      LooooooooooongException {}

After:
  public void doSoooooooooo()
      throws LoooooooooongException, LooooooooooongException {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@222829 91177308-0d34-0410-b5e6-96231b3b80d8