stream_out_std: simplify / factorize
stream_out_std: simplify / factorize

split out some functions from Open()
move static functions
sout_stream_id_t -> define struct as empty and use the pointer to store sout_input_t

functional change:
do not force asfh mux if user specified another one but only warn him (like for upd/ts)

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