Add top level build script for building packages.

ports/gc/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
 
 ConfigureStep() {
   Banner "Configuring ${PACKAGE_NAME}"
   # export the nacl tools
   export CC=${NACLCC}
   export CXX=${NACLCXX}
   export AR=${NACLAR}
   export RANLIB=${NACLRANLIB}
   export PKG_CONFIG_PATH=${NACLPORTS_LIBDIR}/pkgconfig
   export PKG_CONFIG_LIBDIR=${NACLPORTS_LIBDIR}
   export PATH=${NACL_BIN_PATH}:${PATH};
   MakeDir ${NACL_PACKAGES_REPOSITORY}/${PACKAGE_NAME}/${NACL_BUILD_SUBDIR}
   ChangeDir ${NACL_PACKAGES_REPOSITORY}/${PACKAGE_NAME}/${NACL_BUILD_SUBDIR}
   ../configure \
     --host=nacl \
     --prefix=${NACLPORTS_PREFIX} \
     --exec-prefix=${NACLPORTS_PREFIX} \
     --libdir=${NACLPORTS_LIBDIR} \
     --oldincludedir=${NACLPORTS_INCLUDE} \
     --with-http=off \
     --with-html=off \
     --with-ftp=off \
     --enable-threads=pthreads \
     --${NACL_OPTION}-mmx \
     --${NACL_OPTION}-sse \
     --${NACL_OPTION}-sse2 \
     --${NACL_OPTION}-asm \
     --with-x=no
 }
-
-PackageInstall
-exit 0