translator: merge max_insns into DisasContextBase

translator: merge max_insns into DisasContextBase

While at it, use int for both num_insns and max_insns to make
sure we have same-type comparisons.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>