Add new packages and build scripts for various libraries

- Added Nuklear GUI library with build script and configuration.
- Introduced OpenH264 encoder/decoder with build configuration.
- Added PortAudio library for audio I/O with custom build script.
- Included Python Execnet for multi-Python deployment.
- Added Pytest Xdist plugin for distributed testing.
- Introduced Shaderc for shader compilation tools.
- Added Snappy compression library with necessary patches and configuration.
- Included SoundTouch audio processing library with build configuration.
- Added SRT library for secure reliable transport.
- Introduced VapourSynth video processing framework with configuration.
- Added Vid.stab for video stabilization.
- Included WebRTC Audio Processing library with build configuration.
- Added X264 video encoding library with patches for POSIX compliance.
- Introduced X265 video encoder with build configuration.
- Added XKeyboard Config for X keyboard configuration files.
- Included Xorg XKBComp for keyboard description compilation.
- Added Xvidcore MPEG-4 video codec library with configuration.
- Introduced ZeroMQ messaging system with patches and build configuration.
- Added Zimg library for scaling and colorspace conversion.

extra/gavl/gavl.toml

@@ -0,0 +1,35 @@
+[build]
+type = "autotools"
+
+[build.flags]
+configure = ["--with-cpuflags=none"]
+
+[dependencies]
+build = [
+    "doxygen",
+    "libpng",
+]
+runtime = [
+    "glibc",
+    "nettle",
+    "gnutls",
+    "libdrm",
+    "libgl",
+    "libva",
+]
+
+[package]
+description = "Low level library, upon which multimedia APIs can be built"
+homepage = "https://github.com/bplaum/gavl"
+license = "GPL-2.0-or-later"
+name = "gavl"
+version = "2.0.0"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://github.com/bplaum/gavl.git#v$version"
+post_extract = [
+  "autoreconf -fiv",
+  "sed -i 's/^const int gavl_http_response_get_status_int(/int gavl_http_response_get_status_int(/' include/gavl/http.h",
+]
+cherry_pick = [ "0d2fb32914be97da389be4b693de036fd0da5b1b" ]