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/libpaper/libpaper.toml

@@ -0,0 +1,39 @@
+[build]
+type = "autotools"
+
+[build.flags]
+post-compile = [ "cd src && cc $CFLAGS $LDFLAGS -I.. -Ilibgnu -o localepaper localepaper.c libgnu/.libs/libgnupaper.a" ]
+
+post_install = [
+    'install -Dt "$DESTDIR/usr/lib" -m0755 src/localepaper',
+    'install -dm 755 "$DESTDIR"/etc',
+    """echo '# Simply write the paper name. See man 1 paper and "paper --no-size --all" for possible values' > "$DESTDIR"/etc/papersize""",
+    'install -dm 755 "$DESTDIR"/etc/libpaper.d',
+]
+keep = [ "etc/papersize" ]
+
+[dependencies]
+runtime = ["glibc"]
+
+[[manual_sources]]
+file = "localepaper.c"
+
+[package]
+description = "Library for handling paper characteristics"
+homepage = "https://github.com/rrthomas/libpaper"
+license = [
+    "FSFAP",
+    "GPL-3.0-or-later",
+    "LGPL-2.0-or-later",
+    "LGPL-2.1-or-later",
+    "LicenseRef-Public-Domain",
+    "MIT",
+]
+name = "libpaper"
+version = "2.2.7"
+
+[[source]]
+extract_dir = "$name-$version"
+post_extract = ["cp ../localepaper.c src/"]
+sha256 = "3925401edf1eda596277bc2485e050b704fd7f364f257c874b0c40ac5aa627c0"
+url = "https://github.com/rrthomas/libpaper/releases/download/v$version/$name-$version.tar.gz"

extra/libpaper/localepaper.c

@@ -0,0 +1,44 @@
+/*
+ * localepaper: print the dimensions in mm of the current locale's
+ * paper size, if possible.
+ *
+ * Based on a patch by Caolan McNamara:
+ * http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=481213
+ *
+ * Copyright (C) Reuben Thomas <rrt@sc3d.org>, 2013.
+ *
+ * Copying and distribution of this file, with or without modification,
+ * are permitted in any medium without royalty provided the copyright
+ * notice and this notice are preserved.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <locale.h>
+#if defined LC_PAPER && defined _GNU_SOURCE
+#include <langinfo.h>
+#endif
+
+#include "progname.h"
+
+int main(int argc, char *argv[])
+{
+  set_program_name(argv[0]);
+  argc = argc; /* Avoid a compiler warning. */
+
+#if defined LC_PAPER && defined _GNU_SOURCE
+  setlocale(LC_ALL, "");
+
+#define NL_PAPER_GET(x) \
+  ((union { char *string; unsigned word; })nl_langinfo(x)).word
+
+  printf("%d %d\n", NL_PAPER_GET(_NL_PAPER_WIDTH), NL_PAPER_GET(_NL_PAPER_HEIGHT));
+  return EXIT_SUCCESS;
+
+#else
+  printf("%s: locale paper size information is not supported on this system", program_name);
+  return EXIT_FAILURE;
+#endif
+}