hob: use both pre and post files for hob configuration

We need to set various variables *before* parse begins, the simplest way
to ensure this is to use a pre configuration file for the relevant
configuration entries.

This series adapts hob to use both pre and post files to store its
configuration. Any variables which affect initial parse are set in the pre
file and all others in the post file.

Unfortunately this requires hob related code to have even more hard-coded
data as to what is relevant but this is the simplest way to solve issues
with variables and parse order at this time.

Addresses [YOCTO #1281]

(Bitbake rev: 02ab0e11d8dd42f5ca440b3d8d2073e23f55113a)

Signed-off-by: Joshua Lock <josh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/hob.py

@@ -192,8 +192,8 @@ class MainWindow (gtk.Window):
             self.curr_mach = mach
             # Flush this straight to the file as MACHINE is changed
             # independently of other 'Preferences'
-            self.configurator.setLocalConfVar('MACHINE', mach)
-            self.configurator.writeLocalConf()
+            self.configurator.setConfVar('MACHINE', mach)
+            self.configurator.writeConf()
             handler.set_machine(mach)
             handler.reload_data()