clang-format: Avoid line-breaks that increase the current column.

While these might make sense for some rule (e.g. break after multi-line
operand), they generally appear ugly and confusing.

Before:
  fffffffffff(R\"x(
  multiline raw string literal xxxxxxxxxxxxxx
  )x\" + bbbbbb)

After:
  fffffffffff(R\"x(
  multiline raw string literal xxxxxxxxxxxxxx
  )x\" +
              bbbbbb)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@204937 91177308-0d34-0410-b5e6-96231b3b80d8