Match: Add unsigned SAT_MUL for form 7

Match: Add unsigned SAT_MUL for form 7

This patch would like to try to match the the unsigned
SAT_MUL form 7, aka below:

  #define DEF_SAT_U_MUL_FMT_7(NT, WT)             \
  NT __attribute__((noinline))                    \
  sat_u_mul_##NT##_from_##WT##_fmt_7 (NT a, NT b) \
  {                                               \
    WT x = (WT)a * (WT)b;                         \
    NT max = -1;                                  \
    bool overflow_p = x > (WT)(max);              \
    return -(NT)(overflow_p) | (NT)x;             \
  }

while WT is uint128_t, uint64_t, uint32_t and uint16_t, and
NT is uint64_t, uint32_t, uint16_t or uint8_t.

gcc/ChangeLog:

	* match.pd: Add pattern for SAT_MUL form 7 include
	mul and widen_mul.

Signed-off-by: Pan Li <pan2.li@intel.com>