Wayland: Only launch child after OS Window achieves its final size

Avoids a bunch of SIGIWNCH during child startup as not all programs
handle these correctly. Sadly adds about 0.1 seconds of latency to
startup. Will have to look into reducing that. The Wayland protocol is
*so badly* designed.

glfw/glfw.py

@@ -316,6 +316,7 @@ def generate_wrappers(glfw_header: str) -> None:
     void glfwWaylandRedrawCSDWindowTitle(GLFWwindow *handle)
     void glfwWaylandSetupLayerShellForNextWindow(GLFWLayerShellConfig c)
     pid_t glfwWaylandCompositorPID(void)
+    bool glfwWaylandWindowFullyCreated(GLFWwindow *handle)
     unsigned long long glfwDBusUserNotify(const char *app_name, const char* icon, const char *summary, const char *body, \
 const char *action_text, int32_t timeout, GLFWDBusnotificationcreatedfun callback, void *data)
     void glfwDBusSetUserNotificationHandler(GLFWDBusnotificationactivatedfun handler)