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

ports/binutils-2.25/build.sh

 # Copyright 2015 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.
 
 HOST_BUILD_DIR=${WORK_DIR}/build_host
 HOST_INSTALL_DIR=${WORK_DIR}/install_host
 
 export ac_cv_func_getrlimit=no
-export EXTRA_AM_CPPFLAGS="-Dmain=nacl_main"
-export EXTRA_LIBS="${NACL_CLI_MAIN_LIB} -lppapi_simple \
-  -lnacl_io -lppapi -l${NACL_CXX_LIB}"
+
+EnableCliMain
 
 BuildHostBinutils() {
   MakeDir ${HOST_BUILD_DIR}
   ChangeDir ${HOST_BUILD_DIR}
-  CC="gcc" EXTRA_LIBS="" EXTRA_AM_CPPFLAGS="" \
-      LogExecute ${SRC_DIR}/configure --prefix=${HOST_INSTALL_DIR} \
+  LogExecute ${SRC_DIR}/configure --prefix=${HOST_INSTALL_DIR} \
       --target=avr \
       --disable-nls
-  EXTRA_LIBS="" EXTRA_AM_CPPFLAGS="" LogExecute make
-  EXTRA_LIBS="" EXTRA_AM_CPPFLAGS="" LogExecute make install
+  LogExecute make
+  LogExecute make install
 }
 
 ConfigureStep() {
-  ChangeDir ${SRC_DIR}
   BuildHostBinutils
+
   export PATH="${HOST_INSTALL_DIR}/bin:${PATH}"
   ChangeDir ${BUILD_DIR}
   EXTRA_CONFIGURE_ARGS="\
     --target=avr \
     --disable-nls \
     --disable-werror \
     --enable-deterministic-archives \
     --without-zlib"
 
   DefaultConfigureStep
 }