Fix a few warnings

code/qcommon/msg.c

@@ -246,7 +246,7 @@ int MSG_ReadBits( msg_t *msg, int bits ) {
 		}
 		msg->readcount = (msg->bit>>3)+1;
 	}
-	if ( sgn ) {
+	if ( sgn && bits > 0 && bits < 32 ) {
 		if ( value & ( 1 << ( bits - 1 ) ) ) {
 			value |= -1 ^ ( ( 1 << bits ) - 1 );
 		}