gst-examples: add -xobjective-c for darwin

To avoid error when including #include <AppKit/AppKit.h>
the  build should include the c args xobjective-c

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2095>

subprojects/gst-examples/meson.build

@@ -9,6 +9,8 @@ if cc.get_id() == 'msvc'
       language : 'c')
 endif
 
+host_system = host_machine.system()
+
 gst_version = meson.project_version()
 version_arr = gst_version.split('.')
 

subprojects/gst-examples/playback/player/gtk/gtk-play.c

@@ -196,7 +196,7 @@ video_area_realize_cb (GtkWidget * widget, GtkPlay * play)
 #if defined (GDK_WINDOWING_WIN32)
   window_handle = (guintptr) GDK_WINDOW_HWND (window);
 #elif defined (GDK_WINDOWING_QUARTZ)
-  window_handle = gdk_quartz_window_get_nsview (window);
+  window_handle = (guintptr) gdk_quartz_window_get_nsview (window);
 #elif defined (GDK_WINDOWING_X11)
   window_handle = GDK_WINDOW_XID (window);
 #endif

subprojects/gst-examples/playback/player/gtk/meson.build

@@ -1,6 +1,12 @@
 gtk_dep = dependency('gtk+-3.0', required: false)
 x11_dep = dependency('x11', required: false)
 
+if host_system == 'darwin'
+  extra_c_args = ['-xobjective-c']
+else
+  extra_c_args = []
+endif
+
 if gtk_dep.found()
   gnome = import('gnome')
 
@@ -13,5 +19,6 @@ if gtk_dep.found()
         gtk_play_resources,
        'gtk-video-renderer.h',
        'gtk-video-renderer.c'],
+      c_args :  extra_c_args,
       dependencies : [gst_dep, gsttag_dep, gstplay_dep, gtk_dep, x11_dep])
 endif