ffmpeg-5: fix Vulkan builds

- add vulkan-headers as a dependency
- hack around ffmpeg using unstable VK_EXT names for extensions
- drive-by cleanup: remove unused inherit

pkgs/development/libraries/ffmpeg/generic.nix

@@ -253,6 +253,7 @@
 , zeromq4
 , zimg
 , zlib
+, vulkan-headers
 , vulkan-loader
 , glslang
 /*
@@ -286,7 +287,6 @@
  */
 
 let
-  inherit (stdenv) isCygwin isDarwin isFreeBSD isLinux isAarch64;
   inherit (lib) optional optionals optionalString enableFeature;
 in
 
@@ -342,6 +342,10 @@ stdenv.mkDerivation (finalAttrs: {
       --replace /usr/local/lib/frei0r-1 ${frei0r}/lib/frei0r-1
     substituteInPlace doc/filters.texi \
       --replace /usr/local/lib/frei0r-1 ${frei0r}/lib/frei0r-1
+  '' + lib.optionalString withVulkan ''
+    # FIXME: horrible hack, remove for next release
+    substituteInPlace libavutil/hwcontext_vulkan.c \
+      --replace VK_EXT_VIDEO_DECODE VK_KHR_VIDEO_DECODE
   '';
 
   patches = map (patch: fetchpatch patch) extraPatches;
@@ -593,7 +597,7 @@ stdenv.mkDerivation (finalAttrs: {
   ++ optionals withVorbis [ libvorbis ]
   ++ optionals withVpx [ libvpx ]
   ++ optionals withV4l2 [ libv4l ]
-  ++ optionals withVulkan [ vulkan-loader ]
+  ++ optionals withVulkan [ vulkan-headers vulkan-loader ]
   ++ optionals withWebp [ libwebp ]
   ++ optionals withX264 [ x264 ]
   ++ optionals withX265 [ x265 ]