[tracker] Fix build on firefox plugin

[Carlos Garnacho <carlosg src gnome org>]

commit 069f7432d8ea74a5d1328c8b958ce287fc2e68e3
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Feb 13 00:50:55 2014 +0100

    Fix build on firefox plugin
    
    The pl-PL directory was recursed in Makefile, but no Makefile was
    generated on that directory.

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5e986e9..950e47c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2572,6 +2572,7 @@ AC_CONFIG_FILES([
         src/plugins/firefox/chrome/locale/en-US/Makefile
         src/plugins/firefox/chrome/locale/es-ES/Makefile
         src/plugins/firefox/chrome/locale/fr-FR/Makefile
+        src/plugins/firefox/chrome/locale/pl-PL/Makefile
         src/plugins/firefox/chrome/skin/Makefile
         src/plugins/firefox/defaults/Makefile
         src/plugins/firefox/defaults/preferences/Makefile