extras/ios: fix compilation with latest xcode releases
extras/ios: fix compilation with latest xcode releases

(cherry picked from commit 5027938fb4965bca2d3e11ad1c17ca7aecaed258)

jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2