Fix warnings and symbol visibility from missing CFLAGS
diff --git a/compositor/compositor-wayland.c b/compositor/compositor-wayland.c
index b99edf0..1a53e8d 100644
--- a/compositor/compositor-wayland.c
+++ b/compositor/compositor-wayland.c
@@ -465,7 +465,7 @@
 	free(ec);
 }
 
-struct wlsc_compositor *
+static struct wlsc_compositor *
 wayland_compositor_create(struct wl_display *display, int width, int height)
 {
 	struct wayland_compositor *c;
@@ -520,6 +520,9 @@
 }
 
 struct wlsc_compositor *
+backend_init(struct wl_display *display, char *options);
+
+WL_EXPORT struct wlsc_compositor *
 backend_init(struct wl_display *display, char *options)
 {
 	int width = 1024, height = 640, i;