target-arm: fix sdiv helper

(INT32_MIN / -1) triggers an overflow, and the result depends on the
host architecture (INT32_MIN on arm, -1 on ppc, SIGFPE on x86). Use a
test to output the correct value.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Acked-by: Laurent Desnogues <laurent.desnogues@gmail.com>

target-arm/helper.c

@@ -402,6 +402,8 @@ int32_t HELPER(sdiv)(int32_t num, int32_t den)
 {
     if (den == 0)
       return 0;
+    if (num == INT_MIN && den == -1)
+      return INT_MIN;
     return num / den;
 }