libva-v4l2-request-ohm-gl-fix: mark deprecated, point at -fourier

Predecessor experimental package (tarball + 18 stacked patches) is
superseded by libva-v4l2-request-fourier (git-tracked fork tip,
iter38 multi-device probe). The successor already declares
replaces=('libva-v4l2-request-ohm-gl-fix') so installs migrate
automatically; this commit just makes the deprecation visible in
README + pkgdesc.

Kept in-tree as historical reference for the ohm_gl_fix Phase 6
audit trail.

arch/libva-v4l2-request-ohm-gl-fix/PKGBUILD

@@ -1,6 +1,13 @@
 # Maintainer: Markus Fritsche <fritsche.markus@gmail.com>
 # Campaign: ohm_gl_fix Phase 6 Step 1
 #
+# DEPRECATED (2026-05-16): superseded by ../libva-v4l2-request-fourier/
+# which tracks the campaign fork's git history directly and adds the
+# iter38 multi-device probe (single libva session for rkvdec H.264/HEVC/VP9
+# + hantro MPEG-2/VP8). The successor declares
+# replaces=('libva-v4l2-request-ohm-gl-fix'), so installing it removes
+# this package automatically. See README.md for the full deprecation note.
+#
 # Forks libva-v4l2-request to add hantro-vpu multiplanar + modern
 # stateless UAPI support. Conflicts/replaces stock libva-v4l2-request.
 #
@@ -11,7 +18,7 @@ pkgname=libva-v4l2-request-ohm-gl-fix
 _upstreampkg=libva-v4l2-request
 pkgver=1.0.0.r0.ga3c2476
 pkgrel=2
-pkgdesc="VA-API backend for V4L2 stateless decoders, hantro-vpu multiplanar fork"
+pkgdesc="DEPRECATED — use libva-v4l2-request-fourier. VA-API backend for V4L2 stateless decoders, hantro-vpu multiplanar fork"
 arch=('aarch64')
 url="https://github.com/bootlin/libva-v4l2-request"
 license=('LGPL2.1' 'MIT')