Switch from using 'nacl_main' to 'main' entry point

ports/font-util/build.sh

 # 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.
 
 # The host build of this tool is needed by its dependents.
 HOST_BUILD_DIR=${WORK_DIR}/build_host
 HOST_INSTALL_DIR=${WORK_DIR}/install_host
 
 EXECUTABLES="bdftruncate${NACL_EXEEXT} ucs2any${NACL_EXEEXT}"
 
-NACLPORTS_CPPFLAGS+=" -Dmain=nacl_main"
-NACLPORTS_LDFLAGS+=" -Dmain=nacl_main"
-export LIBS="${NACL_CLI_MAIN_LIB}"
+EnableCliMain
 
 EnableGlibcCompat
 
 BuildForHost() {
   Banner "Building for Host"
   MakeDir ${HOST_BUILD_DIR}
   ChangeDir ${HOST_BUILD_DIR}
   CFLAGS="" LDFLAGS="" LIBS="" CC="gcc -m32" \
       LogExecute ${SRC_DIR}/configure --prefix=${HOST_INSTALL_DIR}
   LogExecute make -j${OS_JOBS}
   LogExecute make install
 }
 
 ConfigureStep() {
   BuildForHost
   Banner "Building for NaCl"
   ChangeDir ${BUILD_DIR}
   DefaultConfigureStep
 }