The fallback code in cpu_loop_exit_sigsegv is sufficient
for cris linux-user.

Remove the code from cpu_loop that handled the unnamed 0xaa exception.
This makes all of the code in helper.c sysemu only, so remove the
ifdefs and move the file to cris_softmmu_ss.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>