Allow legacy installed font info distribution file

Because Dompdf allows some customization of its operational parameters a user may load a custom dompdf_font_family_cache.dist.php. If a user has created and is loading such a file, and is using a pre-1.1.0 format, Dompdf will fail to run. This change allows Dompdf to utilize the file regardless of which format it is in.

fixes #2648

src/FontMetrics.php

@@ -133,8 +133,7 @@ public function loadFontFamilies()
 
         $file = $rootDir . "/lib/fonts/dompdf_font_family_cache.dist.php";
         $distFontsClosure = require $file;
-        $distFonts = $distFontsClosure($rootDir);
-
+        $distFonts = is_array($distFontsClosure) ? $distFontsClosure : $distFontsClosure($rootDir);
         if (!is_readable($this->getCacheFile())) {
             $this->fontLookup = $distFonts;
             return;