render/gles2: don't unset the current EGL surface when destroying texture

When a texture is destroyed between wlr_egl_make_current and
wlr_egl_swap_buffers, it resets the current EGL surface to NULL. This
makes wlr_egl_swap_buffers fail.

If the EGL context is already current, there's no need to reset it.

render/gles2/texture.c

@@ -115,7 +115,9 @@ static void gles2_texture_destroy(struct wlr_texture *wlr_texture) {
 
 	struct wlr_gles2_texture *texture = gles2_get_texture(wlr_texture);
 
-	wlr_egl_make_current(texture->egl, EGL_NO_SURFACE, NULL);
+	if (!wlr_egl_is_current(texture->egl)) {
+		wlr_egl_make_current(texture->egl, EGL_NO_SURFACE, NULL);
+	}
 
 	PUSH_GLES2_DEBUG;