Input: attach before any variable access so that inheritance works
Input: attach before any variable access so that inheritance works

So far, the input was attached after it inherited quite a bunch of
variables. This did not quite work. The problem lies in the dual use
of object attachment: variables inheritance and tree search.

Nowadays, the input object should not be looked for before it is
initialized. Only children objects use vlc_object_find anymore, and
they can only exist while the input is fully initialized. Other code
paths use playlist_CurrentInput() or such, which only ever return an
already initialized input (from input.c:Create()).

(N.B.: I wonder if there aren't similar issues in VOUT and AOUT)

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