Fix warnings and symbol visibility from missing CFLAGS

compositor/compositor-drm.c

@@ -627,7 +627,7 @@ drm_destroy(struct wlsc_compositor *ec)
 	free(d);
 }
 
-struct wlsc_compositor *
+static struct wlsc_compositor *
 drm_compositor_create(struct wl_display *display, int connector)
 {
 	struct drm_compositor *ec;
@@ -721,6 +721,9 @@ drm_compositor_create(struct wl_display *display, int connector)
 }
 
 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 connector = 0, i;

compositor/compositor-wayland.c

@@ -465,7 +465,7 @@ wayland_destroy(struct wlsc_compositor *ec)
 	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 @@ wayland_compositor_create(struct wl_display *display, int width, int height)
 }
 
 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;

compositor/compositor-x11.c

@@ -626,7 +626,7 @@ x11_destroy(struct wlsc_compositor *ec)
 	free(ec);
 }
 
-struct wlsc_compositor *
+static struct wlsc_compositor *
 x11_compositor_create(struct wl_display *display, int width, int height)
 {
 	struct x11_compositor *c;
@@ -683,6 +683,9 @@ x11_compositor_create(struct wl_display *display, int width, int height)
 }
 
 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;

compositor/shell.c

@@ -733,6 +733,9 @@ attach(struct wlsc_shell *shell, struct wlsc_surface *surface)
 {
 }
 
+int
+shell_init(struct wlsc_compositor *ec);
+
 WL_EXPORT int
 shell_init(struct wlsc_compositor *ec)
 {