Wayland: Use named constants for version checks

The wayland-scanner output provides really nice, self-documenting
version macros, so we should use them whenever possible.

(cherry picked from commit ed39ff43f9)

src/wl_init.c

@@ -434,8 +434,10 @@ int _glfwPlatformInit(void)
 
     _glfwInitTimerPOSIX();
 
-    if (_glfw.wl.seatVersion >= 4)
+#ifdef WL_KEYBOARD_REPEAT_INFO_SINCE_VERSION
+    if (_glfw.wl.seatVersion >= WL_KEYBOARD_REPEAT_INFO_SINCE_VERSION)
         _glfw.wl.timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK);
+#endif
 
     if (!_glfw.wl.wmBase)
     {

src/wl_window.c

@@ -387,8 +387,7 @@ static void resizeWindow(_GLFWwindow* window)
 
 static void checkScaleChange(_GLFWwindow* window)
 {
-    // Check if we will be able to set the buffer scale or not.
-    if (_glfw.wl.compositorVersion < 3)
+    if (_glfw.wl.compositorVersion < WL_SURFACE_SET_BUFFER_SCALE_SINCE_VERSION)
         return;
 
     // Get the scale factor from the highest scale monitor.