Do not set the APT force-unsafe-io flag

Docker already does this for us. Closes GH-265.

image/cleanup.sh

@@ -7,6 +7,5 @@ apt-get clean
 rm -rf /bd_build
 rm -rf /tmp/* /var/tmp/*
 rm -rf /var/lib/apt/lists/*
-rm -f /etc/dpkg/dpkg.cfg.d/02apt-speedup
 
 rm -f /etc/ssh/ssh_host_*

image/prepare.sh

@@ -3,11 +3,6 @@ set -e
 source /bd_build/buildconfig
 set -x
 
-## Temporarily disable dpkg fsync to make building faster.
-if [[ ! -e /etc/dpkg/dpkg.cfg.d/docker-apt-speedup ]]; then
-	echo force-unsafe-io > /etc/dpkg/dpkg.cfg.d/docker-apt-speedup
-fi
-
 ## Prevent initramfs updates from trying to run grub and lilo.
 ## https://journal.paul.querna.org/articles/2013/10/15/docker-ubuntu-on-rackspace/
 ## http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=594189