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/ffnvcodec-headers/ffnvcodec-headers.toml

@@ -0,0 +1,21 @@
+[build]
+type = "makefile"
+
+[build.flags]
+makefile_commands = [
+    "make PREFIX=/usr",
+    "sed -n '4,25p' include/ffnvcodec/nvEncodeAPI.h > LICENSE",
+    '''sed -i '1,22s/^.\{,3\}//' LICENSE''',
+]
+makefile_install_commands = ['make PREFIX=/usr DESTDIR="$DESTDIR" install']
+
+[package]
+description = "FFmpeg version of headers required to interface with Nvidias codec APIs"
+homepage = "https://git.videolan.org/?p=ffmpeg/nv-codec-headers.git"
+license = "MIT"
+name = "ffnvcodec-headers"
+version = "13.0.19.0"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://git.videolan.org/git/ffmpeg/nv-codec-headers.git#e844e5b26f46bb77479f063029595293aa8f812d"