meson: add option for internal event debugging

These have been behind #if 0 for ages but there are more to come, let's
make it possible to toggle those on/off with a meson option.

This is an option that must not be used in a release build, it will leak
key codes to the logs.

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1156>

meson.build

@@ -353,6 +353,8 @@ else
 endif
 
 ############ libinput.so ############
+config_h.set10('EVENT_DEBUGGING', get_option('internal-event-debugging'))
+
 install_headers('src/libinput.h')
 src_libinput = src_libfilter + [
 	'src/libinput.c',

meson_options.txt

@@ -34,3 +34,7 @@ option('zshcompletiondir',
        type: 'string',
        value: '',
        description: 'Directory for zsh completion scripts ["no" disables]')
+option('internal-event-debugging',
+	type: 'boolean',
+	value: false,
+	description: 'Enable additional internal event debug tracing. This will print key values to the logs and thus must never be enabled in a release build')

src/evdev.c

@@ -1063,7 +1063,7 @@ evdev_process_event(struct evdev_device *device, struct input_event *e)
 	struct evdev_dispatch *dispatch = device->dispatch;
 	uint64_t time = input_event_time(e);
 
-#if 0
+#if EVENT_DEBUGGING
 	evdev_print_event(device, e);
 #endif
 

src/libinput.c

@@ -3193,7 +3193,7 @@ libinput_post_event(struct libinput *libinput,
 	size_t move_len;
 	size_t new_out;
 
-#if 0
+#if EVENT_DEBUGGING
 	libinput_print_queued_event(event);
 #endif