merge r6621 from branch 2.1 to trunk

bug 1742 fixed: if the EXIF functions are not available:

1) display a warning (but not an error)
2) avoid to try to read EXIF data



git-svn-id: http://piwigo.org/svn/trunk@6622 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/functions_upload.inc.php

@@ -141,6 +141,10 @@ function add_uploaded_file($source_filepath, $original_filename=null, $categorie
   }
   
   // update metadata from the uploaded file (exif/iptc)
+  if ($conf['use_exif'] and !function_exists('read_exif_data'))
+  {
+    $conf['use_exif'] = false;
+  }
   update_metadata(array($image_id=>$file_path));
   
   invalidate_user_cache();