Add a FreeBSD build role.

ansible/roles/build/files/freebsd_update_step2

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+#
+# Build and installs whatever is in /usr/src. Run step 1, reboot, then step 2.
+set -euo pipefail
+IFS=$'\n\t'
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+sudo etcupdate -p
+
+cd /usr/src
+sudo make installworld
+sudo etcupdate -B
+
+if sudo etcupdate status | grep -qE '^  C '; then
+    >&2 echo 'Conflicts in etcupdate. Run `etcupdate resolve` to fix them first.'
+    exit 1
+fi
+
+echo "FreeBSD update step 2 done. Please reboot."