Generate locales in debian-based elements

Without generating locales, annoying warnings are spewed.

Change-Id: Ibb2f241a5eb398377967a77cd5dd8fe55719fdbf

elements/debootstrap/install.d/12-debian-locale-gen

@@ -0,0 +1,30 @@
+#!/bin/bash
+#
+# Copyright 2015 Hewlett-Packard Development Company, L.P.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+
+if [ "${DIB_DEBUG_TRACE:-0}" -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+debconf-set-selections - <<EOF
+locales locales/locales_to_be_generated multiselect en_US.UTF-8 UTF-8
+# Choices: None, C.UTF-8, en_US.UTF-8
+locales locales/default_environment_locale select en_US.UTF-8
+EOF
+
+dpkg-reconfigure -f noninteractive locales