Fix prototype to be more const
Fix prototype to be more const

Signed-off-by: David Flynn <38ae1b48ed96d57c9e166f6cc6ffdf619b4856ab@rd.bbc.co.uk>
Signed-off-by: Laurent Aimar <2e4ef4899efb9d4b7a6d090f80ae8072b0abe38d@videolan.org>

vlc-mirror/vlc,krichter722/vlc,xkfz007/vlc,krichter722/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc-2.1,shyamalschandra/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,krichter722/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,shyamalschandra/vlc,vlc-mirror/vlc-2.1,shyamalschandra/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc,vlc-mirror/vlc,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,krichter722/vlc,xkfz007/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,krichter722/vlc,vlc-mirror/vlc,vlc-mirror/vlc-2.1,shyamalschandra/vlc,krichter722/vlc