libgpiosim: new library for controlling the gpio-sim module

Add a C library for controlling the gpio-sim kernel module from various
libgpiod test suites. This aims at replacing the old gpio-mockup module
and its user-space library - libgpio-mockup - in the project's tree.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
7 files changed