share/cairo-util: Use wl_pointer_button_state enum directly

This silences two warnings:

clients/window.c:2450:20: warning: implicit conversion from enumeration
type 'enum wl_pointer_button_state' to different enumeration type 'enum
frame_button_state' [-Wenum-conversion]
                                              button, state);
                                                      ^~~~~

clients/window.c:2453:15: warning: implicit conversion from enumeration
type 'enum wl_pointer_button_state' to different enumeration type 'enum
frame_button_state' [-Wenum-conversion]
                                                button, state);
                                                        ^~~~~

Warning produced by Clang 3.8.

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>
diff --git a/shared/cairo-util.h b/shared/cairo-util.h
index 4fee087..84cf005 100644
--- a/shared/cairo-util.h
+++ b/shared/cairo-util.h
@@ -29,6 +29,7 @@
 #include <stdint.h>
 #include <cairo.h>
 
+#include <wayland-client.h>
 #include <wayland-util.h>
 
 void
@@ -123,11 +124,6 @@
 	FRAME_BUTTON_ALL = 0x7
 };
 
-enum frame_button_state {
-	FRAME_BUTTON_RELEASED = 0,
-	FRAME_BUTTON_PRESSED = 1
-};
-
 struct frame *
 frame_create(struct theme *t, int32_t width, int32_t height, uint32_t buttons,
 	     const char *title);
@@ -208,7 +204,7 @@
  */
 enum theme_location
 frame_pointer_button(struct frame *frame, void *pointer,
-		     uint32_t button, enum frame_button_state state);
+		     uint32_t button, enum wl_pointer_button_state state);
 
 enum theme_location
 frame_touch_down(struct frame *frame, void *data, int32_t id, int x, int y);
@@ -218,7 +214,7 @@
 
 enum theme_location
 frame_double_click(struct frame *frame, void *pointer,
-		   uint32_t button, enum frame_button_state state);
+		   uint32_t button, enum wl_pointer_button_state state);
 
 void
 frame_double_touch_down(struct frame *frame, void *data, int32_t id,