Add top level build script for building packages.

ports/zlib/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
-
+# zlib doesn't support custom build directories so we have
+# to build directly in the source dir.
+BUILD_DIR=${SRC_DIR}
 
 ConfigureStep() {
   Banner "Configuring ${PACKAGE_NAME}"
-  ChangeDir ${NACL_PACKAGES_REPOSITORY}/${PACKAGE_NAME}
+  ChangeDir ${BUILD_DIR}
   LogExecute rm -f libz.*
   # TODO: side-by-side install
   local CONFIGURE_ARGS="--prefix=${NACLPORTS_PREFIX}"
   local CFLAGS="-Dunlink=puts"
   if [ "${NACL_GLIBC}" = "1" -a $# -gt 0 ]; then
       CONFIGURE_ARGS="${CONFIGURE_ARGS} --shared"
       CFLAGS="${CFLAGS} -fPIC"
   fi
   CC=${NACLCC} AR="${NACLAR} -r" RANLIB=${NACLRANLIB} CFLAGS="${CFLAGS}" \
      LogExecute ./configure ${CONFIGURE_ARGS}
   export MAKEFLAGS="EXE=${NACL_EXEEXT}"
   EXECUTABLES="minigzip${NACL_EXEEXT} example${NACL_EXEEXT}"
 }
 
+
 RunMinigzip() {
   export LD_LIBRARY_PATH=.
   if echo "hello world" | ./minigzip | ./minigzip -d; then
     echo '  *** minigzip test OK ***' ; \
       else
     echo '  *** minigzip test FAILED ***' ; \
       exit 1
   fi
   unset LD_LIBRARY_PATH
 }
 
+
 RunExample() {
   export LD_LIBRARY_PATH=.
   # This second test does not yet work on nacl (gzopen fails)
   #if ./example; then \
     #echo '  *** zlib test OK ***'; \
   #else \
     #echo '  *** zlib test FAILED ***'; \
     #exit 1
   #fi
   unset LD_LIBRARY_PATH
 }
 
+
 TestStep() {
   Banner "Testing ${PACKAGE_NAME}"
   if [ "${NACL_GLIBC}" = "1" ]; then
     # Tests do not currently run on GLIBC due to fdopen() not working
     # TODO(sbc): Remove this once glibc is fixed:
     # https://code.google.com/p/nativeclient/issues/detail?id=3362
     return
   fi
 
   if [ $NACL_ARCH = "pnacl" ]; then
@@ skipping 26 matching lines @@
   DefaultPackageInstall
   if [ "${NACL_GLIBC}" = "1" ]; then
     ConfigureStep shared
     BuildStep
     Validate libz.so.1
     ValidateStep
     TestStep
     InstallStep
   fi
 }
-
-
-PackageInstall
-exit 0