build-sys: tell rsync no to tranfer times and permissions

build-sys: tell rsync no to tranfer times and permissions

When rsyncing to fd.o, rsync would fail on symlinks in man/.
We don't care about the times too much anyway. rsync will
set times to "now", which is fine, since modification times
don't matter much outside of each uploader's machine anyway.

The point is to complete all steps of the transfer, so Python
documentation is properly updated.