samples: posix: eventfd: Sample application for eventfd() call.

Roughly based on eventfd example code from Linux manpages. Similarly
to other POSIX-compatible sample, Makefile.posix is provided to build
the code on a POSIX system (in this case, as eventfd() is
Linux-specific, this has to be a Linux system).

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
4 files changed