bitbake: hob: allow configuring default machine using HOB_MACHINE

Allow specifying HOB_MACHINE in local.conf to set the initially
selected machine. With this set, Hob will select the specified machine
and then jump straight into parsing recipes. If you do wish to change
the selected machine with HOB_MACHINE set you still can - you just need
to stop the parsing process first.

Fixes [YOCTO #3148].

(Bitbake rev: c3b623dc7d546a1ededdb532dcbcba4a6230bc65)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

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

@@ -756,6 +756,8 @@ class Builder(gtk.Window):
 
     def handler_command_succeeded_cb(self, handler, initcmd):
         if initcmd == self.handler.GENERATE_CONFIGURATION:
+            if not self.configuration.curr_mach:
+                self.configuration.curr_mach = self.handler.runCommand(["getVariable", "HOB_MACHINE"]) or ""
             self.update_configuration_parameters(self.get_parameters_sync())
             self.sanity_check()
         elif initcmd == self.handler.SANITY_CHECK: