tcg/s390x: fix constraint for 32-bit TSTEQ/TSTNE

tcg/s390x: fix constraint for 32-bit TSTEQ/TSTNE

32-bit TSTEQ and TSTNE is subject to the same constraints as
for 64-bit, but setcond_i32 and negsetcond_i32 were incorrectly
using TCG_CT_CONST ("i") instead of TCG_CT_CONST_CMP ("C").

Adjust the constraint and make tcg_target_const_match use the
same sequence as tgen_cmp2: first check if the constant is a
valid operand for TSTEQ/TSTNE, then accept everything for 32-bit
non-test comparisons, finally check if the constant is a valid
operand for 64-bit non-test comparisons.

Reported-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>