target/arm: Vectorize integer comparison vs zero

target/arm: Vectorize integer comparison vs zero

These instructions are often used in glibc's string routines.
They were the final uses of the 32-bit at a time neon helpers.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200418162808.4680-1-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>