Change the processing time for search_task and exif_task to start the

1.5 second counter only after we've done any expensive queries.  This
guarantees at least some time to do work.

Fixes ticket #693.

modules/exif/helpers/exif_task.php

@@ -50,12 +50,18 @@ class exif_task_Core {
                ->orwhere("exif_records.dirty", 1)
                ->close_paren()
                ->find_all() as $item) {
+        // The query above can take a long time, so start the timer after its done
+        // to give ourselves a little time to actually process rows.
+        if (!isset($start)) {
+          $start = microtime(true);
+        }
+
+        exif::extract($item);
+        $completed++;
+
         if (microtime(true) - $start > 1.5) {
           break;
         }
-
-        $completed++;
-        exif::extract($item);
       }
 
       list ($remaining, $total, $percent) = exif::stats();