Add top level build script for building packages.

ports/pcre/build.sh

 #!/bin/bash
 # Copyright (c) 2013 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
-
 # There are two additional tests (RunGrepTest and RunTest shell scripts) that
 # make check does but it would be hard to run it here. Especially the first one.
 TestStep() {
   # test only pnacl and if target and host architectures match
   if [ "${NACL_ARCH}" = "pnacl" ]; then
     for test in pcre_scanner_unittest.* pcre_stringpiece_unittest.* pcrecpp_unittest.*; do
         RunSelLdrCommand ${test}
     done
     echo "Tests OK"
   elif [ `uname -m` == "${NACL_ARCH_ALT}" ]; then
     for test in pcre_scanner_unittest.* pcre_stringpiece_unittest.* pcrecpp_unittest.*; do
         # use the binary in .libs instead if there is any
         if [ -e .libs/${test} ]; then
           (cd .libs;
             WriteSelLdrScript run_${test} ${test};
             ./run_${test})
         else
           WriteSelLdrScript run_${test} ${test}
           ./run_${test}
         fi
     done
     echo "Tests OK"
   fi
 }
-
-DefaultPackageInstall
-exit 0