Use fold instead of passing a wrap length to base64.

The base64 implementation included with MacOS 10.7 doesn't
support the -w option for wrapping lines. Using the fold
command is more portable.

doc/build_draft.sh

@@ -35,7 +35,7 @@ cp -a "${toplevel}"/COPYING "${destdir}"/COPYING
 
 tar czf opus_source.tar.gz "${destdir}"
 echo building base64 version
-cat opus_source.tar.gz| base64 -w 66 | sed 's/^/###/' > opus_source.base64
+cat opus_source.tar.gz| base64 | fold -w 66 | sed 's/^/###/' > opus_source.base64
 
 #echo '<figure>' > opus_compare_escaped.c
 #echo '<artwork>' >> opus_compare_escaped.c