ifcvt: Move noce_try_cond_zero_arith last

ifcvt: Move noce_try_cond_zero_arith last

I noticed that on x86_64 and aarch64, noce_try_cond_zero_arith
would produce worse code than noce_try_cmove_arith.
So we should do noce_try_cond_zero_arith last instead
of before noce_try_cmove_arith.

Pushed as obvious after bootstrap/test on x86_64-linux-gnu.
Also checked to make sure riscv testcases still work.

gcc/ChangeLog:

	* ifcvt.cc (noce_process_if_block): Move noce_try_cond_zero_arith
	last.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>