SCUMM: Fix random number generation in SCUMM6

Now it matches disassembly and particularly fixes RNG in
Backyard Sports games.

engines/scumm/script_v6.cpp

@@ -1345,8 +1345,8 @@ void ScummEngine_v6::o6_loadRoomWithEgo() {
 }
 
 void ScummEngine_v6::o6_getRandomNumber() {
-	int rnd;
-	rnd = _rnd.getRandomNumber(ABS(pop()));
+	int rnd = _rnd.getRandomNumber(0x7fff);
+	rnd = rnd % (pop() + 1);
 	if (VAR_RANDOM_NR != 0xFF)
 		VAR(VAR_RANDOM_NR) = rnd;
 	push(rnd);
@@ -1355,7 +1355,8 @@ void ScummEngine_v6::o6_getRandomNumber() {
 void ScummEngine_v6::o6_getRandomNumberRange() {
 	int max = pop();
 	int min = pop();
-	int rnd = _rnd.getRandomNumberRng(min, max);
+	int rnd = _rnd.getRandomNumber(0x7fff);
+	rnd = min + (rnd % (max - min + 1));
 	if (VAR_RANDOM_NR != 0xFF)
 		VAR(VAR_RANDOM_NR) = rnd;
 	push(rnd);
@@ -2901,10 +2902,10 @@ void ScummEngine_v6::o6_delayFrames() {
 	// WORKAROUND:  At startup, Moonbase Commander will pause for 20 frames before
 	// showing the Infogrames logo.  The purpose of this break is to give time for the
 	// GameSpy Arcade application to fill with the Online game infomation.
-	// 
+	//
 	// [0000] (84) localvar2 = max(readConfigFile.number(":var263:","user","wait-for-gamespy"),10)
 	// [0029] (08) delayFrames((localvar2 * 2))
-	// 
+	//
 	// But since we don't support GameSpy and have our own Online support, this break
 	// has become redundant and only wastes time.
 	if (_game.id == GID_MOONBASE && vm.slot[_currentScript].number == 69) {