lavu: avoid clashing definition of E

E is usually defined as a shorthand for AV_OPT_FLAG_ENCODING_PARAM.
Rename the single expansion E(x) now used in libavutil to E1.
8svx: decode directly to the user-provided AVFrame
aac: decode directly to the user-provided AVFrame
ac3: decode directly to the user-provided AVFrame
adpcm: decode directly to the user-provided AVFrame
adx: decode directly to the user-provided AVFrame
adxenc: alloc/free coded_frame instead of keeping it in the ADXContext
alac: decode directly to the user-provided AVFrame
als: decode directly to the user-provided AVFrame
amrnb: decode directly to the user-provided AVFrame
amrwb: decode directly to the user-provided AVFrame
ape: decode directly to the user-provided AVFrame
atrac1: decode directly to the user-provided AVFrame
atrac3: decode directly to the user-provided AVFrame
binkaudio: decode directly to the user-provided AVFrame
pcm: decode directly to the user-provided AVFrame
bmvaudio: decode directly to the user-provided AVFrame
comfortnoise: decode directly to the user-provided AVFrame
cook: decode directly to the user-provided AVFrame
dca: decode directly to the user-provided AVFrame