libweston: make weston_output::connection_internal a bool

It really is a boolean.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Armin Krezović <krezovic.armin@gmail.com>
diff --git a/libweston/compositor.h b/libweston/compositor.h
index 0be9157..442d046 100644
--- a/libweston/compositor.h
+++ b/libweston/compositor.h
@@ -223,7 +223,7 @@
 	void (*set_backlight)(struct weston_output *output, uint32_t value);
 	void (*set_dpms)(struct weston_output *output, enum dpms_enum level);
 
-	int connection_internal;
+	bool connection_internal;
 	uint16_t gamma_size;
 	void (*set_gamma)(struct weston_output *output,
 			  uint16_t size,