clang-format: Fix bug in handling of single-column lists.

Members that are themselves wrapped in fake parentheses would lead to
AvoidBinPacking be set on the wrong ParenState.

After:
  vector<int> aaaa = {
      aaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
      aaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
      aaaaaa.aaaaaaa,
      aaaaaa.aaaaaaa,
      aaaaaa.aaaaaaa,
      aaaaaa.aaaaaaa,
  };

Before we were falling back to bin-packing these.

llvm-svn: 290259