Fix xlib bustage.

Thanks to Roland Mainz <Roland.Mainz@informatik.med.uni-giessen.de> for the patch.
Bug #135441 r=cls

embedding/components/build/Makefile.in

@@ -87,6 +87,10 @@ ifeq ($(MOZ_GFX_TOOLKIT),gtk)
 LOCAL_INCLUDES += -I$(srcdir)/../printingui/src/gtk 
 endif
 
+ifeq ($(MOZ_GFX_TOOLKIT),xlib)
+LOCAL_INCLUDES += -I$(srcdir)/../printingui/src/gtk 
+endif
+
 ifeq ($(MOZ_GFX_TOOLKIT),beos)
 LOCAL_INCLUDES += -I$(srcdir)/../printingui/src/gtk 
 endif

embedding/components/printingui/src/Makefile.in

@@ -30,6 +30,10 @@ ifdef MOZ_ENABLE_GTK
 DIRS        += gtk
 endif
 
+ifdef MOZ_ENABLE_XLIB
+DIRS        += gtk
+endif
+
 ifdef MOZ_ENABLE_QT
 DIRS        += gtk
 endif