Split do_unit_cond to do_unit_zero_cond to only handle conditions
versus zero. These are the only ones that are legal for UXOR.
Simplify trans_uxor accordingly.
Rename do_unit to do_unit_addsub, since xor has been split.
Properly compute carry-out bits for add and subtract, mirroring
the code in do_add and do_sub.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Fixes: b2167459ae ("target-hppa: Implement basic arithmetic")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>