Function sub_bits

cpp/fory/util/float16_test.cc:734–736

  return float16_t::add(H(a), H(b)).to_bits();
}
static uint16_t sub_bits(uint16_t a, uint16_t b) {
  return float16_t::sub(H(a), H(b)).to_bits();
}
static uint16_t mul_bits(uint16_t a, uint16_t b) {
  return float16_t::mul(H(a), H(b)).to_bits();
}