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/avisynthplus/avisynthplus.toml

@@ -0,0 +1,40 @@
+[build]
+type = "cmake"
+
+[build.flags]
+build_dir = "build"
+configure = ["-Wno-dev", '-DCMAKE_CXX_FLAGS="-I/usr/include/soundtouch"']
+post_install = [ "install -D -m644 ../avisynthplus.xml -t $DESTDIR/usr/share/mime/packages" ]
+
+[dependencies]
+build = [
+    "cmake",
+    "soundtouch",
+    "devil",
+]
+optional = [
+    "devil",
+    "soundtouch",
+]
+runtime = [
+    "glibc",
+    "hicolor-icon-theme",
+    "libunwind",
+    "libcxx",
+]
+
+[package]
+description = "An improved version of the AviSynth frameserver"
+homepage = "https://avs-plus.net/"
+license = "GPL-2.0-or-later"
+name = "avisynthplus"
+version = "3.7.5"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://github.com/AviSynth/AviSynthPlus.git#v$version"
+patches = [ "010-avisynthplus-fix-symbol-conflict-with-vmaf.patch" ]
+post_extract = [ "rm avs_core/include/avisynth.h.orig" ]
+
+[[manual_sources]]
+files = [ "avisynthplus.xml", "010-avisynthplus-fix-symbol-conflict-with-vmaf.patch" ]