Add top level build script for building packages.

ports/tinyxml/build.sh

 #!/bin/bash
 # Copyright (c) 2011 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 
-source pkg_info
-source ../../build_tools/common.sh
 
 
 BuildStep() {
   Banner "Building ${PACKAGE_NAME}"
   ChangeDir ${NACL_PACKAGES_REPOSITORY}/${PACKAGE_NAME}
   export CC=${NACLCC}
   export CXX=${NACLCXX}
   export AR=${NACLAR}
   export LD=${NACLLD}
   export RANLIB=${NACLRANLIB}
   make clean
   make OUTPUT=libtinyxml.a
 }
 
 
 InstallStep() {
   # copy libs and headers manually
   Banner "Installing ${PACKAGE_NAME} to ${NACLPORTS_PREFIX}"
   ChangeDir ${NACLPORTS_INCLUDE}
   Remove ${PACKAGE_NAME}
   MakeDir ${PACKAGE_NAME}
   readonly THIS_PACKAGE_PATH=${NACL_PACKAGES_REPOSITORY}/${PACKAGE_NAME}
   cp ${THIS_PACKAGE_PATH}/*.h ${PACKAGE_NAME}/
   ChangeDir ${NACLPORTS_LIBDIR}
   cp ${THIS_PACKAGE_PATH}/*.a .
 }
-
-
-PackageInstall
-exit 0