mac/common: add support for force-render option

DOCS/man/options.rst

@@ -3648,7 +3648,7 @@ Window
 
 ``--force-render``
     Forces mpv to always render frames regardless of the visibility of the
-    window. Currently only affects X11 and Wayland VOs since they are the
+    window. Currently only affects X11, Wayland and macvk VOs since they are the
     only ones that have this optimization (i.e. everything else always renders
     regardless of visibility).
 

video/out/mac_common.swift

@@ -110,7 +110,7 @@ class MacCommon: Common {
     }
 
     @objc func isVisible() -> Bool {
-        return window?.occlusionState.contains(.visible) ?? false
+        return window?.occlusionState.contains(.visible) ?? false || option.vo.force_render
     }
 
     override func displayLinkCallback(_ displayLink: CVDisplayLink,