Extend splitter pattern to reversed condition by swapping then and else rtx. [PR target/104982]

Failed to match this instruction:
(set (reg/v:SI 88 [ z ])
    (if_then_else:SI (eq (zero_extract:SI (reg:SI 92)
                (const_int 1 [0x1])
                (zero_extend:SI (subreg:QI (reg:SI 93) 0)))
            (const_int 0 [0]))
        (reg:SI 95)
        (reg:SI 94)))

but it's equal to

(set (reg/v:SI 88 [ z ])
    (if_then_else:SI (ne (zero_extract:SI (reg:SI 92)
                (const_int 1 [0x1])
                (zero_extend:SI (subreg:QI (reg:SI 93) 0)))
            (const_int 0 [0]))
        (reg:SI 94)
        (reg:SI 95)))

which is the exact existing splitter.

The patch will fix below regressions:

On x86-64, r12-7687 caused:

FAIL: gcc.target/i386/bt-5.c scan-assembler-not sar[lq][ \t]
FAIL: gcc.target/i386/bt-5.c scan-assembler-times bt[lq][ \t] 7

gcc/ChangeLog:

	PR target/104982
	* config/i386/i386.md (*jcc_bt<mode>_mask): Extend the
	following splitter to reversed condition.