postproc: allow the use of 'thumb' if we don't specify 'small'
postproc: allow the use of 'thumb' if we don't specify 'small'

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