Don't build demo Linux printing plugin by default. b=573945 r=jst

modules/plugin/Makefile.in

@@ -49,10 +49,6 @@ DIRS		= base/public
 ifdef MOZ_PLUGINS
 DIRS		+= base/src 
 
-ifeq ($(MOZ_WIDGET_TOOLKIT),gtk2)
-TOOL_DIRS += sdk/samples/unixprinting
-endif
-
 # These subdirs rely on GTK libraries and header files, it is not
 #  buildable on other non-GTK unix builds