clang-format: Fix corner case in "if it saves columns"-calculation.

Before:
  aaaa
      .aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
	  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)
      .aaaaaa(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);

After:
  aaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
	  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)
      .aaaaaa(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);

llvm-svn: 256841