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/jack2/build.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+set -eu
+
+depot_build() {
+    rm -rf ./waflib
+
+    export CXXFLAGS="${CXXFLAGS:+$CXXFLAGS }-I/usr/include/db5.3"
+    export LDFLAGS="${LDFLAGS:+$LDFLAGS }-ldb-5.3"
+    export LINKFLAGS="$LDFLAGS"
+    export PYTHONPATH="${PWD}${PYTHONPATH:+:$PYTHONPATH}"
+
+    waf configure \
+        --prefix=/usr \
+        --htmldir=/usr/share/doc/jack2/html \
+        --autostart=none \
+        --doxygen=yes \
+        --classic \
+        --dbus
+
+    waf build
+}
+
+depot_install() {
+    export PYTHONPATH="${PWD}${PYTHONPATH:+:$PYTHONPATH}"
+    waf install --destdir="$DESTDIR"
+
+    install -Dm755 ../jackd.initd "$DESTDIR/etc/init.d/jackd"
+    install -Dm644 ../jackd.confd "$DESTDIR/etc/conf.d/jackd"
+    install -d "$DESTDIR/etc/jack"
+}

extra/jack2/jack2-1.9.22-db-5.3.patch

@@ -0,0 +1,15 @@
+diff --git i/wscript w/wscript
+index 86eb3954..bdd29dc3 100644
+--- i/wscript
++++ w/wscript
+@@ -199,8 +199,8 @@ def options(opt):
+     db = opt.add_auto_option(
+             'db',
+             help='Use Berkeley DB (metadata)')
+-    db.check(header_name='db.h')
+-    db.check(lib='db')
++    db.check(header_name='db5.3/db.h')
++    db.check(lib='db-5.3')
+ 
+     # dbus options
+     opt.recurse('dbus')

extra/jack2/jack2.toml

@@ -0,0 +1,45 @@
+[alternatives]
+conflicts = ["pipewire-jack"]
+provides = ["jack"]
+
+[build.flags]
+keep = [ "etc/conf.d/jackd" ]
+
+[build]
+type = "custom"
+
+[dependencies]
+build = [
+    "doxygen",
+    "expat",
+    "waf",
+]
+optional = [
+    "a2jmidid",
+    "realtime-privileges",
+]
+runtime = [
+    "alsa-lib",
+    "db5.3",
+    "dbus",
+    "glibc",
+    "libunwind",
+    "libsamplerate",
+    "libcxx",
+    "opus",
+]
+
+[[manual_sources]]
+files = [ "jack2-1.9.22-db-5.3.patch", "jackd.initd", "jackd.confd", "build.sh" ]
+
+[package]
+description = "The JACK low-latency audio server"
+homepage = "https://github.com/jackaudio/jack2"
+license = "GPL-2.0-or-later"
+name = "jack2"
+version = "1.9.22"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://github.com/jackaudio/jack2.git#v$version"
+patches = [ "jack2-1.9.22-db-5.3.patch" ]

extra/jack2/jackd.confd

@@ -0,0 +1,13 @@
+# Extra jackd options
+JACK_OPTIONS=""
+
+# Driver, usually alsa
+DRIVER="alsa"
+
+# Device, for example:
+# DEVICE="hw:0"
+DEVICE="hw:0"
+
+# Extra driver settings, for example:
+# DRIVER_SETTINGS="-r 48000 -p 1024 -n 2"
+DRIVER_SETTINGS=""

extra/jack2/jackd.initd

@@ -0,0 +1,54 @@
+#!/sbin/openrc-run
+
+name="JACK server"
+description="JACK server using a named profile"
+
+profile="${RC_SVCNAME#jackd.}"
+[ "$profile" = "$RC_SVCNAME" ] && profile="default"
+
+conf_file="/etc/jack/${profile}.conf"
+user_conf="/home/${SVCNAME_USER:-$profile}/.config/jack/${profile}.conf"
+
+command="/usr/bin/jackd"
+command_background="yes"
+pidfile="/run/${RC_SVCNAME}.pid"
+
+depend() {
+    need localmount
+    use alsasound dbus
+}
+
+start_pre() {
+    if [ -f "$conf_file" ]; then
+        . "$conf_file"
+    elif [ -f "$user_conf" ]; then
+        . "$user_conf"
+    fi
+
+    : "${JACK_OPTIONS:=}"
+    : "${DRIVER:=alsa}"
+    : "${DEVICE:=hw:0}"
+    : "${DRIVER_SETTINGS:=}"
+
+    command_args="$JACK_OPTIONS -d $DRIVER -d $DEVICE $DRIVER_SETTINGS"
+}
+
+start() {
+    checkpath -d -m 0755 /run
+    ulimit -r 95 || true
+    ulimit -l unlimited || true
+    ebegin "Starting ${RC_SVCNAME}"
+    start-stop-daemon \
+        --start \
+        --background \
+        --make-pidfile \
+        --pidfile "$pidfile" \
+        --exec "$command" -- $command_args
+    eend $?
+}
+
+stop() {
+    ebegin "Stopping ${RC_SVCNAME}"
+    start-stop-daemon --stop --pidfile "$pidfile" --retry TERM/5
+    eend $?
+}