add a way to extract variables from config_host/build and shell-export them

usage:
. ./bin/get_config_variables [ --host | --build ] variable [variable ...]

--host is the default

Change-Id: I37d90faf613dfbdb060c18e25370175fde26f3bf

bin/get_config_variables

+#!/bin/sh
+#set -x
+
+glv_var="$1"
+glv_config="config_host.mk"
+
+if [ "$glv_var" = "--build" ] ; then
+    glv_config="config_build.mk"
+    shift
+elif [ "$glv_var" = "--host" ] ; then
+    shift
+fi
+
+while [ -n "$1" ] ; do
+    glv_var="$1"
+    shift
+    glv_value=$(grep "^ *export ${glv_var}=" ${glv_config} | sed -e "s/[^=]*=//")
+    export ${glv_var}="${glv_value}"
+done
+
+unset glv_var
+unset glv_value
+unset glv_vonfig