target/sh4: Fix mac.w with saturation enabled

The saturation arithmetic logic in helper_macw is not correct.
I tested and verified this behavior on a SH7091.

Reviewd-by: Yoshinori Sato <ysato@users

target/sh4: Fix mac.w with saturation enabled

The saturation arithmetic logic in helper_macw is not correct.
I tested and verified this behavior on a SH7091.

Reviewd-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Zack Buhman <zack@buhman.org>
Message-Id: <20240405233802.29128-3-zack@buhman.org>
[rth: Reformat helper_macw, add a test case.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

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