snow: update to buffer refs
dxa: fix compilation
eacmv: fix compilation
eamad: fix compilation
eatgv: fix compilation
escape124: remove unused variable.

This also broke compilation in MSVC because it mixed declarations and code.
escape130: convert to refcounted frames
evrcdec: convert to refcounted frames
exr: convert to refcounted frames
vp3: resolve conflicts (ASSISTANCE NEEDED).

- One copy_fields() chunk change get dropped and was security relevant (247d30a7).
- Not sure if change from d5efa84f will get honored properly.