fix warming for ICU tokenizer

Running the warm-up search requests requires querying
the most frequent words. This must be done via the tokenizer
to honor the different formats of the word table.

lib-php/tokenizer/legacy_tokenizer.php

@@ -48,6 +48,14 @@ class Tokenizer
     }
 
 
+    public function mostFrequentWords($iNum)
+    {
+        $sSQL = 'SELECT word FROM word WHERE word is not null ';
+        $sSQL .= 'ORDER BY search_name_count DESC LIMIT '.$iNum;
+        return $this->oDB->getCol($sSQL);
+    }
+
+
     public function tokensForSpecialTerm($sTerm)
     {
         $aResults = array();