clang-format: Increase penalty for wrapping array subscript expressions

Before:
  aaaaaaaaaaa aaaaaaaaaaaaaaa = aaaaaaaaaaaaaaaaaaaaaaaaaa->aaaaaaaaa[0].aaaaaaa
                                    [0].aaaaaaaaaaaaaaaaaaaaaa();

After:
  aaaaaaaaaaa aaaaaaaaaaaaaaa = aaaaaaaaaaaaaaaaaaaaaaaaaa->aaaaaaaaa[0]
                                    .aaaaaaa[0]
                                    .aaaaaaaaaaaaaaaaaaaaaa();

llvm-svn: 210529