Normally main.c file doesn't have a header, beacuse it doesn't need to
be declared to other modules.
And in this sample it makes more sense to use name msgdev.h instead of
main.h as the header file for msgdev.c.
Signed-off-by: Paul He <pawpawhe@gmail.com>
Set integration_platforms on these samples to just native_posix. This
should be sufficient to make sure these tests build and run.
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>