bitbake: hob/hobpages: Generate the title label every time

- the title label is destroyed at page switching (that's why we need
to generate it every time)

[YOCTO #3195]

(Bitbake rev: d6d991c08f66cf9ab27c53075109212ea9129380)

Signed-off-by: Constantin Musca <constantinx.musca@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/crumbs/hobpages.py

@@ -62,6 +62,7 @@ class HobPage (gtk.VBox):
 
         hbox = gtk.HBox()
 
+        self.title_label = gtk.Label()
         self.title_label.set_markup("<span size='x-large'>%s</span>" % self.title)
         hbox.pack_start(self.title_label, expand=False, fill=False, padding=20)