fixing thunderbird/gtk2 bustage from bug 333640: link to $(TK_LIBS) on gtk2

as well, like in browser/components/build/Makefile.in

mail/components/build/Makefile.in

@@ -85,8 +85,9 @@ EXTRA_DSO_LDOPTS += \
 	$(MOZ_COMPONENT_LIBS) \
 	$(NULL)
 
-# Need to link to CoreFoundation for Mac shell service
-ifneq (,$(filter mac cocoa,$(MOZ_WIDGET_TOOLKIT)))
+# Mac: Need to link to CoreFoundation for Mac shell service
+# GTK2: Need to link with glib for GNOME shell service
+ifneq (,$(filter mac cocoa gtk2,$(MOZ_WIDGET_TOOLKIT)))
 EXTRA_DSO_LDOPTS += \
   $(TK_LIBS) \
   $(NULL)