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

ports/python3/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.
 
 EXECUTABLES=python${NACL_EXEEXT}
 
-NACLPORTS_CPPFLAGS+=" -Dmain=nacl_main"
-
 # Currently this package only builds on linux.
 # The build relies on certain host binaries and python's configure
 # requires us to set --build= as well as --host=.
 
 HOST_BUILD_DIR=${WORK_DIR}/build_host
 export PATH=${HOST_BUILD_DIR}/inst/usr/local/bin:${PATH}
 
 SetOptFlags() {
   # Python build system sets its own opt flags
   return
@@ skipping 26 matching lines @@
   if [ "${NACL_DEBUG}" = 1 ]; then
     EXTRA_CONFIGURE_ARGS+=" --with-pydebug"
   fi
   if [ "${TOOLCHAIN}" = "glibc" -a "${NACL_ARCH}" = "arm" ]; then
     # Ignore sys/xattr.h, since glibc/arm toolchain does not define
     # XATTR_SIZE_MAX:
     # https://code.google.com/p/nativeclient/issues/detail?id=4300
     export ac_cv_header_sys_xattr_h=no
   fi
   NACLPORTS_LIBS+=" -ltermcap"
-  NACLPORTS_LIBS+=" ${NACL_CLI_MAIN_LIB}"
   if [ "${NACL_LIBC}" = "newlib" ]; then
     # When python builds with wait3/wait4 support it also expects struct rusage
     # to have certain fields and newlib lacks.
     export ac_cv_func_wait3=no
     export ac_cv_func_wait4=no
   fi
+  EnableCliMain
   EnableGlibcCompat
   DefaultConfigureStep
   if [ "${NACL_LIBC}" = "newlib" ]; then
     LogExecute cp ${START_DIR}/Setup.local Modules/
   fi
 }
 
 BuildStep() {
   export CROSS_COMPILE=true
   export MAKEFLAGS="PGEN=${HOST_BUILD_DIR}/Parser/pgen"
@@ skipping 43 matching lines @@
   InstallNaClTerm ${assembly_dir}
   LogExecute cp ${START_DIR}/background.js ${assembly_dir}
   LogExecute cp ${START_DIR}/python.js ${assembly_dir}
   LogExecute cp ${START_DIR}/index.html ${assembly_dir}
   LogExecute cp ${START_DIR}/icon_16.png ${assembly_dir}
   LogExecute cp ${START_DIR}/icon_48.png ${assembly_dir}
   LogExecute cp ${START_DIR}/icon_128.png ${assembly_dir}
   ChangeDir ${PUBLISH_DIR}
   CreateWebStoreZip python3-${VERSION}.zip python3
 }