clang-format: Prefer an additional line-break over hanging indent.

Don't allow the RHS of an operator to be split over multiple
lines unless there is a line-break right after the operator.

Before:
  if (aaaa && bbbbb || // break
                  cccc) {
  }

After:
  if (aaaa &&
      bbbbb || // break
          cccc) {
  }

In most cases, this seems to increase readability.

llvm-svn: 205527