Also make olddefconfig after merging arch and board defconfig

We create a .config from the arch defconfig, then append
board/defconfig to it. If board/defconfig enables new options
that brings in new sub-options an interactive prompt is shown
when building. Example: Adding CONFIG_USB_SERIAL=m gives

* Restart config...
* USB Serial Converter support
USB Serial Converter support (USB_SERIAL) [M/n/y/?]

Two problems with this:
- Interacting with the build isn't very efficient
- The docker build isn't actually interactive, responses
  to stdin aren't piped through so one can't progress and
  such new options can't be enabled in board defconfig.

Making olddefconfig solves both issues by automatically picking
the default options for any new options made available in

Change-Id: Id69310f2af62e1e9036195ec216219f4f1e74fbd
1 file changed