configure: docbook2x for future ctng

configure

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-set -eu
+set -eux
 all=false
 apt_get=true
 baremetal=false
@@ -76,31 +76,36 @@ fi
 
 if "$apt_get"; then
   pkgs="\
-  automake \
-  bc \
-  build-essential \
-  coreutils \
-  cpio \
-  expect \
-  git \
-  moreutils \
-  rsync \
-  tmux \
-  unzip \
-  vinagre \
-  wget \
-  "
+automake \
+bc \
+build-essential \
+coreutils \
+cpio \
+expect \
+git \
+moreutils \
+rsync \
+tmux \
+unzip \
+vinagre \
+wget \
+"
   if "$gem5"; then
-    pkgs="$pkgs \
-  ccache \
-  gcc-aarch64-linux-gnu \
-  gcc-arm-linux-gnueabi \
-  libgoogle-perftools-dev \
-  protobuf-compiler \
-  python-dev \
-  python-pip \
-  scons \
-  "
+    pkgs="${pkgs} \
+ccache \
+gcc-aarch64-linux-gnu \
+gcc-arm-linux-gnueabi \
+libgoogle-perftools-dev \
+protobuf-compiler \
+python-dev \
+python-pip \
+scons \
+"
+  fi
+  if "$baremetal"; then
+    pkgs="${pkgs} \
+docbook2x \
+"
   fi
   command -v apt-get >/dev/null 2>&1 || {
     cat <<EOF