Avoid modulo operation in loop in array_chunk

For this benchmark:
```php
$length = 25;
for ($i=0;$i<1000;$i++)
  array_chunk(range(0, 10000), $length);
```

On an i7-4790, length=25 speeds up by 1.8x and length=1 by 1.27x.
On an i7-1185G7, length=25 speeds up by 1.08x and length=1 by 1.02x.

ext/standard/array.c

@@ -7046,9 +7046,10 @@ PHP_FUNCTION(array_chunk)
 
 		/* If reached the chunk size, add it to the result array, and reset the
 		 * pointer. */
-		if (!(++current % size)) {
+		if (++current == size) {
 			add_next_index_zval(return_value, &chunk);
 			ZVAL_UNDEF(&chunk);
+			current = 0;
 		}
 	} ZEND_HASH_FOREACH_END();