MDL-78957 libraries: Fix php82 undefined property deprecation

This was detected only in master (4.3dev) because MDL-40084
added a unit test covering it. But the very same patch is
needed in 402_STABLE, no matter it's not covered there.

Author: stronk7

lib/odslib.class.php

@@ -120,6 +120,10 @@ class MoodleODSWorksheet {
     public $rows = array();
     public $showgrid = true;
     public $name;
+    /** @var int Max number of rows in the sheet. */
+    public $maxr = 0;
+    /** @var int Max number of cols in the sheet. */
+    public $maxc = 0;
 
     /**
      * Constructs one Moodle Worksheet.
@@ -864,8 +868,6 @@ protected function get_ods_content() {
         $colstyles = '';
 
         foreach($this->worksheets as $wsnum=>$ws) {
-            $this->worksheets[$wsnum]->maxr = 0;
-            $this->worksheets[$wsnum]->maxc = 0;
             foreach($ws->data as $rnum=>$row) {
                 if ($rnum > $this->worksheets[$wsnum]->maxr) {
                     $this->worksheets[$wsnum]->maxr = $rnum;