Bug#11866367 FPE WHEN SETTING INNODB_SPIN_WAIT_DELAY

rb://865
approved by: Jimmy

Integer overflow causes division by zero.

storage/innobase/include/ut0rnd.ic

@@ -96,7 +96,7 @@ ut_rnd_interval(
 
 	rnd = ut_rnd_gen_ulint();
 
-	return(low + (rnd % (high - low + 1)));
+	return(low + (rnd % (high - low)));
 }
 
 /*************************************************************

storage/innodb_plugin/include/ut0rnd.ic

@@ -114,7 +114,7 @@ ut_rnd_interval(
 
 	rnd = ut_rnd_gen_ulint();
 
-	return(low + (rnd % (high - low + 1)));
+	return(low + (rnd % (high - low)));
 }
 
 /*********************************************************//**