clang-format: Format long lists in columns if without bin-packing.

After (even with BinPacking = false):
  const Aaaaaa aaaaa = {
      aaaaa,  bbbbb,  ccccc,  ddddd,  eeeee,  ffffff, ggggg, hhhhhh,
      iiiiii, jjjjjj, kkkkkk, aaaaa,  bbbbb,  ccccc,  ddddd, eeeee,
      ffffff, ggggg,  hhhhhh, iiiiii, jjjjjj, kkkkkk,
  };

Before:
  <each element on its own line>

This fixes http://llvm.org/PR20623.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215529 91177308-0d34-0410-b5e6-96231b3b80d8