toytoolkit: Don't draw shadows for maximized windows.

Add THEME_FRAME_MAXIMIZED flag so the theming system can know not to draw
shadows for maximized windows. This allows maximized surfaces' content to be
sized and placed in a more expectable fashion.
diff --git a/src/xwayland/window-manager.c b/src/xwayland/window-manager.c
index f5571a5..6d4ce1b 100644
--- a/src/xwayland/window-manager.c
+++ b/src/xwayland/window-manager.c
@@ -1034,7 +1034,7 @@
 static int
 get_cursor_for_location(struct theme *t, int width, int height, int x, int y)
 {
-	int location = theme_get_location(t, x, y, width, height);
+	int location = theme_get_location(t, x, y, width, height, 0);
 
 	switch (location) {
 		case THEME_LOCATION_RESIZING_TOP:
@@ -1101,7 +1101,7 @@
 		location = theme_get_location(t,
 					      button->event_x,
 					      button->event_y,
-					      width, height);
+					      width, height, 0);
 
 		switch (location) {
 		case THEME_LOCATION_TITLEBAR: