Reduce penalty for splitting after "{" in static initializers.

This fixes llvm.org/PR15379.

Before:
const uint8_t aaaaaaaaaaaaaaaaaaaaaa[0] = { 0x00, 0x00, 0x00, 0x00, 0x00,
                                            0x00,                  // comment
                                            0x00, 0x00, 0x00, 0x00, 0x00,
                                            0x00,                  // comment
                                            0x00, 0x00, 0x00, 0x00 // comment
};

After:
const uint8_t aaaaaaaaaaaaaaaaaaaaaa[0] = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // comment
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // comment
  0x00, 0x00, 0x00, 0x00              // comment
};