Add atxmega-a1u-xpro board to BOARD_INSUFFICIENT_MEMORY list to
exclude test since boards don't have enough data memory.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
Proto files can include other proto files.
E.g. nanopb comes with a `nanopb.proto` include that contains some
nanopb-specific extensions.
This patch makes it possible to include this file as well as specifying
additional proto include folders.
I added the include to `simple.proto` so it gets exercised by the test.
