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

ports/tree/build.sh

Index: ports/tree/build.sh
diff --git a/ports/tree/build.sh b/ports/tree/build.sh
index bc8b20dcc041a0b6c7b0cb6f593c44c0a8810c47..1259682bc3a3ebe91911d7381609eccf837329f4 100644
--- a/ports/tree/build.sh
+++ b/ports/tree/build.sh
@@ -2,12 +2,12 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-NACLPORTS_CFLAGS+=" -Dmain=nacl_main"
 BUILD_DIR=${SRC_DIR}
 EXECUTABLES="tree"
-NACLPORTS_LDFLAGS+=" ${NACL_CLI_MAIN_LIB}"
 INSTALL_TARGETS="install prefix=${DESTDIR}/${PREFIX}"
 
+EnableCliMain
+
 BuildStep() {
   LogExecute make clean
   LogExecute make -j${OS_JOBS} CC="${NACLCC}" CFLAGS=" -c \