Fix multiplex backreferences near end of string in regexp match

See https://bugs.ruby-lang.org/issues/18631

See ruby/ruby#5710

Author: headius

src/org/joni/ByteCodeMachine.java

@@ -1442,7 +1442,7 @@ private void opBackRefMulti() {
             int pend = backrefEnd(mem);
 
             int n = pend - pstart;
-            if (s + n > range) {opFail(); return;}
+            if (s + n > range) continue;
 
             sprev = s;
             int swork = s;
@@ -1478,7 +1478,7 @@ private void opBackRefMultiIC() {
             int pend = backrefEnd(mem);
 
             int n = pend - pstart;
-            if (s + n > range) {opFail(); return;}
+            if (s + n > range) continue;
 
             sprev = s;