Following the instructions at http://bazel.io/docs/install.html for a Mac using macports, I get:
$ ./compile.sh
cp: /include/archive.h: No such file or directory
cp: /include/archive_entry.h: No such file or directory

This seems to fix the problem:

$ git diff ./compile.sh
diff --git a/compile.sh b/compile.sh
index c4ff9bf..3a9231a 100755
--- a/compile.sh
+++ b/compile.sh
@@ -99,7 +99,8 @@ EOF

   elif [[ -e $macports_header ]]; then
     # For use with Macports.

•    archive_dir=$(dirname $(dirname $macports_header)) rm -f fromhost/*.[ah]
  

•    archive_dir=$(dirname $(dirname $macports_header))
  

•    rm -f fromhost/*.[ah]
   touch fromhost/empty.c
   cp "${archive_dir}"/include/{archive.h,archive_entry.h} fromhost/
   cp "${archive_dir}"/lib/{libarchive,liblzo2,liblzma,libcharset,libbz2,libxml2,libz,libiconv}.a \