build: allow to build the package in a clean container.

dists/build/archlinux/Dockerfile

@@ -0,0 +1,13 @@
+FROM archlinux:base-devel
+
+RUN pacman -Syu --noconfirm --noprogressbar --quiet \
+        devtools git pacman-contrib \
+        go git rsync lsb-release && \
+    paccache -r -k 0 && \
+    pacman -Rscn --noconfirm --noprogressbar pacman-contrib && \
+    useradd -m -s /bin/bash -u 1000 build && \
+    echo "build ALL=NOPASSWD: ALL" >> /etc/sudoers && \
+    chown -R build:build /home/build
+
+USER build
+CMD ["/bin/bash"]