Contribs: disable vpx encoders with --disable-sout
Contribs: disable vpx encoders with --disable-sout

(cherry picked from commit 5f7cb6f8b1864563652954a0d5d667bebb2583ee)
Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

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