ffmpeg-v4l2-request-fourier: export ff_h264_set_mb_inspect_cb (0016 amend, PKGREL 15)

The 0016 patch declared ff_h264_set_mb_inspect_cb in h264dec.h and
defined it in h264_mb.c, but didn't touch libavcodec/libavcodec.v.
FFmpeg's default version script exports only `av_*`, `avcodec_*`,
`avpriv_*`, and `avsubtitle_free`; everything else is hidden as LOCAL
behind a `*` glob.  Result: `nm -D libavcodec.so.62 | grep
ff_h264_set_mb_inspect_cb` returned nothing → dlsym() returned NULL.

Static-link CLI consumer (daedalus_decode_h264) was unaffected
because static linking doesn't care about symbol visibility.  The
daedalus-v4l2 daemon shadow_decoder path (PR-Q3a.1) dlopens
libavcodec.so.62 and resolves the callback via dlsym — that needs
the symbol exported.

Fix: add ff_h264_set_mb_inspect_cb to the global list in
libavcodec/libavcodec.v.  Single-line addition to the 0016 patch.
Mirrored across the arch/ + debian/ patch trees.

PKGREL bump 14 → 15, changelog entry added (debian side).  PKGBUILD
pkgrel bumped on arch side too.  No behaviour change to the decode
path: the callback is still opt-in via the H264Context function
pointer; only consumers that have explicitly installed a callback
pay the one-load-one-branch cost per MB.

dejavu-check: this is fixing the existing 0016 observation-hook to
actually work as a dlsym intercept (the architectural shape the
patch was designed for).  NOT adding new per-kernel substitution.
Same shape, same patch number, same intent.  Just hiding/exporting
plumbing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

arch/ffmpeg-v4l2-request-fourier/0016-h264-mb-inspect-callback.patch

@@ -35,13 +35,20 @@ to fall through.
 
 Used by:
   - daedalus-decoder/tools/daedalus_decode_h264 (PR-A1b)
-  - future daedalus-v4l2 daemon refactor
+  - daedalus-v4l2 daemon shadow-mode path (PR-Q3a.1+)
+
+The CLI static-links libavcodec.a so symbol visibility doesn't matter
+there.  The daemon dlopens libavcodec.so.62 and resolves the callback
+via dlsym, so the symbol MUST be exported — added to libavcodec.v
+explicitly (FFmpeg's default version script hides every `ff_*` symbol
+as LOCAL behind a glob).
 
 Refs reauktion/daedalus-decoder!12 (Stage 2 PR-b complete).
 ---
- libavcodec/h264_mb.c | 20 ++++++++++++++++++++
- libavcodec/h264dec.h | 26 ++++++++++++++++++++++++++
- 2 files changed, 46 insertions(+)
+ libavcodec/h264_mb.c    | 20 ++++++++++++++++++++
+ libavcodec/h264dec.h    | 26 ++++++++++++++++++++++++++
+ libavcodec/libavcodec.v |  1 +
+ 3 files changed, 47 insertions(+)
 
 --- a/libavcodec/h264dec.h
 +++ b/libavcodec/h264dec.h
@@ -113,3 +120,13 @@ Refs reauktion/daedalus-decoder!12 (Stage 2 PR-b complete).
 +    h->mb_inspect_cb     = cb;
 +    h->mb_inspect_opaque = opaque;
  }
+--- a/libavcodec/libavcodec.v
++++ b/libavcodec/libavcodec.v
+@@ -3,6 +3,7 @@
+         av_*;
+         avcodec_*;
+         avpriv_*;
++        ff_h264_set_mb_inspect_cb;
+         avsubtitle_free;
+     local:
+         *;

arch/ffmpeg-v4l2-request-fourier/PKGBUILD

@@ -24,7 +24,7 @@ _srcname=FFmpeg
 _version='8.1'
 _commit='b57fbbe50c9b2656fad86a1a7eeabfd2b2a50935'  # v4l2-request-n8.1 tip 2026-04-24
 pkgver=8.1.r123329.b57fbbe
-pkgrel=14  # pkgrel=14 — per-MB coefficient side buffer (0017) extending 0016 for daedalus-decoder CLI IDCT validation; observation-only, no behaviour change to existing decode path
+pkgrel=15  # pkgrel=15 — export ff_h264_set_mb_inspect_cb via libavcodec.v so dlsym consumers (daedalus-v4l2 daemon shadow_decoder, PR-Q3a.1) can resolve the symbol; static-link CLI was unaffected. No behaviour change to existing decode path. (2026-05-26)
 epoch=2
 
 # daedalus-fourier pin.  209a421 = PR #2 merge (Phase 8c — public API