clang-format: Fix trailing const (etc.) with Allman brace style.

Before:
  void someLongFunction(int someLongParameter)
      const
  {
  }

After:
  void someLongFunction(
      int someLongParameter) const
  {
  }

This fixes llvm.org/PR19912.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210010 91177308-0d34-0410-b5e6-96231b3b80d8