bitbake: bitbake & hob: modify some commands and call them from hob

This patch adds a new command to create an extra configuration
file, in order to create it from Hob.
Also, it calls the enable/disable data tracking when needed.
Modified the prefiles and postfiles variables because the cooker
expects some lists.

(Bitbake rev: 92393701adcfa181a1090e3632bc6df7ee7852e6)

Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

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

@@ -454,7 +454,9 @@ class HobHandler(gobject.GObject):
         return " ".join(ret)
 
     def set_var_in_file(self, var, val, default_file=None):
+        self.runCommand(["enableDataTracking"])
         self.server.runCommand(["setVarFile", var, val, default_file])
+        self.runCommand(["disableDataTracking"])
 
     def get_parameters(self):
         # retrieve the parameters from bitbake