Add some speedups to dpkg

The docker build folks obsess about image size and speed a bit. Grab a
few of their optimizations from their debootstrap build process and
apply them to ours.

Change-Id: Ic3d3565423b0ae090896d99fd3bf1145eca6303d

elements/dpkg/cleanup.d/60-untrim-dpkg

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -eu
+set -o pipefail
+
+[ -n "$TARGET_ROOT" ]
+
+sudo rm $TARGET_ROOT/etc/dpkg/dpkg.cfg.d/02apt-speedup
+sudo rm $TARGET_ROOT/etc/apt/apt.conf.d/no-languages

elements/dpkg/root.d/99-trim-dpkg

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -eu
+set -o pipefail
+
+[ -n "$TARGET_ROOT" ]
+
+# During image build, sync calls are expensive overhead
+echo 'force-unsafe-io' | sudo tee $TARGET_ROOT/etc/dpkg/dpkg.cfg.d/02apt-speedup > /dev/null
+
+# and remove the translations, too
+echo 'Acquire::Languages "none";' | sudo tee $TARGET_ROOT/etc/apt/apt.conf.d/no-languages > /dev/null