Use cp -a instead of cp -ar.

ports/emacs/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.
 
 OS_JOBS=1
 
 export RUNPROGRAM="${NACL_SDK_ROOT}/tools/sel_ldr.py"
 
 EXTRA_CONFIGURE_ARGS+=" --prefix=/usr --exec-prefix=/usr"
 
@@ skipping 80 matching lines @@
 
   if [ ${EMACS_X:-0} = 1 ]; then
     EMACS_NAME="EmacsXWindows"
   else
     EMACS_NAME="Emacs"
   fi
 
   # Copy all installed files into tarball
   MakeDir ${ASSEMBLY_DIR}/emacstar/usr
   ChangeDir ${ASSEMBLY_DIR}/emacstar
-  LogExecute cp -ar ${DESTDIR}${PREFIX}/* ./usr
+  LogExecute cp -a ${DESTDIR}${PREFIX}/* ./usr
   LogExecute cp usr/bin/emacs${NACL_EXEEXT} \
        ../emacs_${NACL_ARCH}${NACL_EXEEXT}
   rm -rf usr/bin
   rm -rf usr/share/man
   find . -iname "*.nexe" -delete
   mkdir -p ${ASSEMBLY_DIR}/emacstar/home/user/.emacs.d
   tar cf ${ASSEMBLY_DIR}/emacs.tar .
   rm -rf ${ASSEMBLY_DIR}/emacstar
   shasum ${ASSEMBLY_DIR}/emacs.tar > ${ASSEMBLY_DIR}/emacs.tar.hash
   cd ${ASSEMBLY_DIR}
@@ skipping 24 matching lines @@
     fi
     LogExecute cp ${XORG_DIR}/*.tar ${ASSEMBLY_DIR}/
     LogExecute cp ${XORG_DIR}/*.js ${ASSEMBLY_DIR}/
     LogExecute cp ${XORG_DIR}/*.html ${ASSEMBLY_DIR}/
 
     LogExecute cp ${START_DIR}/../emacs-x/Xsdl.js ${ASSEMBLY_DIR}/
   fi
   ChangeDir ${PUBLISH_DIR}
   CreateWebStoreZip emacs-${VERSION}.zip emacs
 }