gles2: Avoid crash when glGetInteger64vEXT is missing

The spec for GL_EXT_disjoint_timer_query says

> The GetInteger64vEXT command is required only if OpenGL ES 3.0 or later
> is not supported.

Some GLES 3.2 implementations like the proprietary mali driver on the
rk3566 based OrangePi advertise GL_EXT_disjoint_timer_query but lack
glGetInteger64vEXT. Use glGetInteger64v instead.

render/gles2/renderer.c

@@ -614,7 +614,11 @@ struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_egl *egl) {
 		load_gl_proc(&renderer->procs.glQueryCounterEXT, "glQueryCounterEXT");
 		load_gl_proc(&renderer->procs.glGetQueryObjectivEXT, "glGetQueryObjectivEXT");
 		load_gl_proc(&renderer->procs.glGetQueryObjectui64vEXT, "glGetQueryObjectui64vEXT");
-		load_gl_proc(&renderer->procs.glGetInteger64vEXT, "glGetInteger64vEXT");
+		if (eglGetProcAddress("glGetInteger64vEXT")) {
+			load_gl_proc(&renderer->procs.glGetInteger64vEXT, "glGetInteger64vEXT");
+		} else {
+			load_gl_proc(&renderer->procs.glGetInteger64vEXT, "glGetInteger64v");
+		}
 	}
 
 	if (renderer->exts.KHR_debug) {