add ability to override pacman mirror in devtools configuration

This commit also extends configuration of the multilib option, adding
the ability to exlcude multilib repository from repositories list

Note, that in order to support repository list and mirror correctly,
alpm configuration section is now architectture specific

docker/entrypoint.sh

@@ -39,6 +39,12 @@ chown "$AHRIMAN_USER":"$AHRIMAN_USER" "$AHRIMAN_GNUPG_HOME"
 AHRIMAN_SETUP_ARGS=("--build-as-user" "$AHRIMAN_USER")
 AHRIMAN_SETUP_ARGS+=("--packager" "$AHRIMAN_PACKAGER")
 AHRIMAN_SETUP_ARGS+=("--repository" "$AHRIMAN_REPOSITORY")
+if [ -z "$AHRIMAN_MULTILIB" ]; then
+    AHRIMAN_SETUP_ARGS+=("--no-multilib")
+fi
+if [ -n "$AHRIMAN_PACMAN_MIRROR" ]; then
+    AHRIMAN_SETUP_ARGS+=("--mirror" "$AHRIMAN_PACMAN_MIRROR")
+fi
 if [ -n "$AHRIMAN_PORT" ]; then
     AHRIMAN_SETUP_ARGS+=("--web-port" "$AHRIMAN_PORT")
 fi