Client examples using wlr_egl would fail with EGL_BAD_CONFIG because they
need an EGL config. Set the config attribs to a non-NULL value to make
sure wlr_egl creates an EGL config.
Fixes: 037710b1d4 ("render/egl: support config-less wlr_egl")
Again, copy'n'search'n'replace the idle inhibit example to become a
simple keyboard shortcuts inhibit example, adding the active and
inactive events.
Getting the initial inhibitor needs to be done later than for idle
inhibit to avoid an error "xdg_surface has never been configured".
Signed-off-by: Michael Weiser <michael.weiser@gmx.de>