Add `makecontainerpkg`

* Allow building Arch Linux packages within a "standard" container similar
  to how `makechrootpkg` allows building packages within a systemd-nspawn
  container
* Add a Dockerfile to create an Arch Linux image suitable for package
  builds via `makepkg`

devel/container/base-devel/Dockerfile

@@ -0,0 +1,10 @@
+FROM archlinux:base as base
+MAINTAINER Martchus <martchus@gmx.net>
+
+RUN mkdir -p /startdir /build && \
+    useradd -m -d /build -u 1000 -U -s /bin/bash builduser && \
+    chown -R builduser:builduser /build && \
+    pacman -Syu --noconfirm --needed base-devel pacman-contrib && \
+    pacman -Scc --noconfirm && \
+    paccache -r -k0 && \
+    rm -rf /usr/share/man/* /tmp/* /var/tmp/*

devel/container/containerbuild

@@ -0,0 +1,8 @@
+#!/bin/bash
+set -e
+source PKGBUILD
+pacman -Syu --noconfirm --needed "${depends[@]}" "${makedepends[@]}" "${checkdepends[@]}"
+export LOGDEST=$PWD SRCPKGDEST=$PWD SRCDEST=$PWD PKGDEST=$PWD BUILDDIR=/build
+export BUILDTOOL=makecontainerbuild BUILDTOOLVER="0.0.1"
+chown builduser:builduser "$PWD"
+sudo --preserve-env=LOGDEST,SRCPKGDEST,SRCDEST,PKGDEST,BUILDDIR,BUILDTOOL,BUILDTOOLVER --user builduser makepkg

devel/container/imagebuild

@@ -0,0 +1,4 @@
+#!/bin/bash
+set -e
+bindir=$(dirname "$0")
+"${CRE:-docker}" image build --tag "${CRE_IMAGE:-archlinux-base-devel}" "$bindir/base-devel"

devel/container/makecontainerpkg

@@ -0,0 +1,28 @@
+#!/bin/bash
+set -e
+
+# load "containerbuild" script
+bindir=$(dirname "$0")
+script=$(cat "$bindir/containerbuild")
+
+# parse arguments
+cre_args=(--workdir "/startdir" -v "$PWD":/startdir --rm)
+script_args= read_script_args=
+for arg in "$@"; do
+    if [[ $read_script_args ]]; then
+        script_args+=" '$arg'"
+    else
+        if [[ $arg == '--' ]]; then
+            read_script_args=1
+        else
+            cre_args+=("$arg")
+        fi
+    fi
+done
+
+# allow one to prevent the container from stopping via DEBUG variable
+if [[ $DEBUG ]]; then
+    script_args+=' ; sleep infinity'
+fi
+
+"${CRE:-docker}" run "${cre_args[@]}" "${CRE_IMAGE:-archlinux-base-devel}" bash -c "$script $script_args"