target/arm: Fix SVE signed division vs x86 overflow exception

target/arm: Fix SVE signed division vs x86 overflow exception

We already check for the same condition within the normal integer
sdiv and sdiv64 helpers.  Use a slightly different formation that
does not require deducing the expression type.

Fixes: f97cfd596ed
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20180629001538.11415-2-richard.henderson@linaro.org
[PMM: reworded a comment]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>