Platform-dependent header ignore list for gio docs

This is a bit awkward. A more elegant solution would have
ignored *all* headers and then *un-ignored* some of them
if some conditions were met.

Sadly, we cannot really ignore all headers and then "unignore"
them: that's not how arrays in Meson work.

https://bugzilla.gnome.org/show_bug.cgi?id=794557

docs/reference/gio/meson.build

@@ -55,7 +55,6 @@ if get_option('gtk_doc')
     'gnetworkmonitorportal.h',
     'gnotificationbackend.h',
     'gnotification-private.h',
-    'gosxappinfo.h',
     'gpollfilemonitor.h',
     'gproxyresolverportal.h',
     'gregistrysettingsbackend.h',
@@ -76,9 +75,7 @@ if get_option('gtk_doc')
     'gunixvolume.h',
     'gunixvolumemonitor.h',
     'gwin32appinfo.h',
-    'gwin32inputstream.h',
     'gwin32mount.h',
-    'gwin32outputstream.h',
     'gwin32registrykey.h',
     'gwin32resolver.h',
     'gwin32volumemonitor.h',
@@ -86,6 +83,34 @@ if get_option('gtk_doc')
     'xdp-dbus.h',
   ]
 
+  if host_system == 'windows'
+    ignore_headers += [
+      'gfiledescriptorbased.h',
+      'gunixconnection.h',
+      'gunixcredentialsmessage.h',
+      'gunixmounts.h',
+      'gunixfdlist.h',
+      'gunixfdmessage.h',
+      'gunixinputstream.h',
+      'gunixoutputstream.h',
+      'gunixsocketaddress.h',
+      'gdesktopappinfo.h',
+      'gosxappinfo.h',
+    ]
+  else
+    if glib_have_cocoa
+      ignore_headers += ['gdesktopappinfo.h']
+    else
+      ignore_headers += ['gosxappinfo.h']
+    endif
+
+    ignore_headers += [
+      'gwin32networkmonitor.h',
+      'gwin32inputstream.h',
+      'gwin32outputstream.h',
+    ]
+  endif
+
   ignore_decorators = [
     'GLIB_VAR',
     'G_GNUC_INTERNAL',