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

ports/pkg/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.
 
 EXECUTABLES="src/pkg${NACL_EXEEXT}"
-export LIBS+="-lbsd ${NACL_CLI_MAIN_LIB} -pthread"
+NACLPORTS_LIBS+=" -lbsd -pthread"
 
 EXTRA_CONFIGURE_ARGS+=" --prefix=/usr --exec-prefix=/usr"
-NACLPORTS_CFLAGS+=" -Dmain=nacl_main"
 
 if [ "${NACL_SHARED}" = "1" ]; then
-  LIBS+=" -lresolv -ldl -lrt"
+  NACLPORTS_LIBS+=" -lresolv -ldl -lrt"
   EXECUTABLES+=" src/pkg-static${NACL_EXEEXT}"
   EXTRA_CONFIGURE_ARGS+=" --enable-shared=yes --with-staticonly=no"
   NACLPORTS_CPPFLAGS+=" -D_GNU_SOURCE"
 else
   EXTRA_CONFIGURE_ARGS+=" --enable-shared=no --with-staticonly=yes"
 fi
 
+EnableCliMain
 EnableGlibcCompat
 
 ConfigureStep() {
   ChangeDir ${SRC_DIR}
   ./autogen.sh
   PatchConfigure
   ChangeDir ${BUILD_DIR}
   DefaultConfigureStep
 }
 
@@ skipping 11 matching lines @@
     LDFLAGS+=" -L${libbsd_install}/usr/local/lib"
 
     cd ${HOST_BUILD_DIR}
     LogExecute ${SRC_DIR}/configure
     LogExecute make -j${OS_JOBS}
     cd -
   fi
 }
 
 BuildStep() {
-  (unset LIBS && BuildHost)
+  (BuildHost)
   DefaultBuildStep
   if [ "${NACL_SHARED}" = "0" ]; then
     LogExecute mv src/pkg-static${NACL_EXEEXT} src/pkg${NACL_EXEEXT}
   fi
 }
 
 TestStep() {
   if [[ ${TOOLCHAIN} = pnacl ]]; then
     return
   fi
   if [[ ${NACL_SHARED} = 1 ]]; then
     LogExecute ${BUILD_DIR}/src/pkg-static -v
   else
     LogExecute ${BUILD_DIR}/src/pkg -v
   fi
 }
 
 InstallStep() {
   DefaultInstallStep
   LogExecute mv ${DESTDIR}/usr ${DESTDIR}/${PREFIX}
   if [ "${NACL_SHARED}" = "0" ]; then
       LogExecute mv ${DESTDIR}/${PREFIX}/sbin/pkg-static${NACL_EXEEXT}\
          ${DESTDIR}/${PREFIX}/sbin/pkg${NACL_EXEEXT}
   fi
 }
 
 PublishStep() {
   PublishMultiArch src/pkg-static${NACL_EXEEXT} pkg
 }