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

ports/gforth/build.sh

 # Copyright (c) 2014 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.
 
 # NOTE: This build doesn't work in parallel.
 OS_JOBS=1
 
 # This build relies on certain host binaries.
 HOST_BUILD_DIR=${WORK_DIR}/build_host
 HOST_INSTALL_DIR=${WORK_DIR}/install_host
 
 EXECUTABLES="gforth-ditc${NACL_EXEEXT}"
 MAKE_TARGETS="${EXECUTABLES}"
 
+EnableCliMain
+
 BuildHostGforth() {
   MakeDir ${HOST_BUILD_DIR}
   ChangeDir ${HOST_BUILD_DIR}
   CC="gcc -m32" \
       LogExecute ${SRC_DIR}/configure --prefix=${HOST_INSTALL_DIR}
   LogExecute make -j${OS_JOBS}
   LogExecute make install
 }
 
 ConfigureStep() {
   ChangeDir ${SRC_DIR}
   ./autogen.sh
   BuildHostGforth
   export PATH="${HOST_INSTALL_DIR}/bin:${PATH}"
   export skipcode=no
-  NACLPORTS_CPPFLAGS+=" -Dmain=nacl_main"
-  export LIBS+=" -Wl,--undefined=nacl_main ${NACL_CLI_MAIN_LIB} \
-      -ltar -lppapi_simple -lnacl_io -lppapi -l${NACL_CXX_LIB}"
   EnableGlibcCompat
   ChangeDir ${BUILD_DIR}
   EXTRA_CONFIGURE_ARGS="--without-check"
   DefaultConfigureStep
 }
 
 BuildStep() {
   rm -f gforth
   DefaultBuildStep
   cp ${MAKE_TARGETS} gforth
@@ skipping 27 matching lines @@
   LogExecute python ${TOOLS_DIR}/create_term.py gforth.nmf
 
   InstallNaClTerm ${PUBLISH_DIR}
 
   cp ${START_DIR}/gforth.js ${PUBLISH_DIR}/
 
   ChangeDir ${PUBLISH_DIR}
   Remove gforth.zip
   LogExecute zip -r gforth.zip .
 }