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

ports/gtk+/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.
 
 ConfigureStep() {
   if [ "${NACL_LIBC}" = "newlib" ]; then
     # newlib requires different library order to deal with static libraries
     NACLPORTS_LIBS+=" -lXext -lX11 -lxcb -lXau"
   fi
 
   EnableGlibcCompat
+  EnableCliMain
 
   EXTRA_CONFIGURE_ARGS+=" --disable-shm --enable-explicit-deps --disable-cups \
    --enable-gtk-doc-html=no"
 
-  NACLPORTS_CPPFLAGS+=" -Dmain=nacl_main -pthread"
-  NACLPORTS_LDFLAGS+=" ${NACL_CLI_MAIN_LIB}"
   export enable_gtk_doc=no
 
   DefaultConfigureStep
 }
 
 PublishStep() {
   MakeDir ${PUBLISH_DIR}
   local FONT_ROOT_DIR="${PUBLISH_DIR}/${NACL_ARCH}/root"
   local FONTCONFIG_DIR="${START_DIR}/../fontconfig"
   local FONT_CACHE="${NACL_PACKAGES_PUBLISH}/xfonts/${TOOLCHAIN}/${NACL_ARCH}"
@@ skipping 76 matching lines @@
   LogExecute cp ${INSTALL_DIR}/naclports-dummydir/bin/gtk-demo${NACL_EXEEXT} \
    ${exe}
   LogExecute python ${NACL_SDK_ROOT}/tools/create_nmf.py \
           ${exe} -s . -L ${INSTALL_DIR}/naclports-dummydir/lib \
           -o gtk-demo.nmf
   LogExecute python ${TOOLS_DIR}/create_term.py -n gtk-demo gtk-demo.nmf
   InstallNaClTerm ${APP_DIR}
   LogExecute cp -f ${START_DIR}/*.js ${APP_DIR}
   LogExecute rm -rf ${FONT_ROOT_DIR}
 }