Fix a few -pedantic warnings

We're not enabling -pedantic by default, but a quick test brought up a few
issues that we should fix.
diff --git a/src/compositor-wayland.c b/src/compositor-wayland.c
index 69135a9..96fedbc 100644
--- a/src/compositor-wayland.c
+++ b/src/compositor-wayland.c
@@ -46,7 +46,7 @@
 	struct weston_compositor	 base;
 
 	struct wl_egl_pixmap		*dummy_pixmap;
-	EGLSurface			 dummy_egl_surface;;
+	EGLSurface			 dummy_egl_surface;
 
 	struct {
 		struct wl_display *display;