Make session optional

include/sway/server.h

@@ -3,7 +3,6 @@
 #include <stdbool.h>
 #include <wayland-server-core.h>
 #include <wlr/backend.h>
-#include <wlr/backend/session.h>
 #include <wlr/render/allocator.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_compositor.h>

sway/input/keyboard.c

@@ -1,8 +1,8 @@
 #include <assert.h>
 #include <limits.h>
 #include <strings.h>
+#include <wlr/config.h>
 #include <wlr/backend/multi.h>
-#include <wlr/backend/session.h>
 #include <wlr/interfaces/wlr_keyboard.h>
 #include <wlr/types/wlr_idle.h>
 #include <wlr/types/wlr_keyboard.h>
@@ -16,6 +16,10 @@
 #include "sway/ipc-server.h"
 #include "log.h"
 
+#if WLR_HAS_SESSION
+#include <wlr/backend/session.h>
+#endif
+
 static struct modifier_key {
 	char *name;
 	uint32_t mod;
@@ -264,10 +268,12 @@ static bool keyboard_execute_compositor_binding(struct sway_keyboard *keyboard,
 		xkb_keysym_t keysym = pressed_keysyms[i];
 		if (keysym >= XKB_KEY_XF86Switch_VT_1 &&
 				keysym <= XKB_KEY_XF86Switch_VT_12) {
+#if WLR_HAS_SESSION
 			if (server.session) {
 				unsigned vt = keysym - XKB_KEY_XF86Switch_VT_1 + 1;
 				wlr_session_change_vt(server.session, vt);
 			}
+#endif
 			return true;
 		}
 	}