third_party: Update waf to version 2.0.17

third_party: Update waf to version 2.0.17

This fixes building Samba, libtalloc, libtevent, libtdb and libldb with
Python 3.8.

     wget https://waf.io/waf-2.0.17.tar.bz2
     tar -xf waf-2.0.17.tar.bz2
     git rm third_party/waf/waflib/ -r
     mkdir third_party/waf -p
     rsync -a waf-2.0.17/waflib/ third_party/waf/waflib/
     git add third_party/waf/waflib/

(Then update version number in buildtools/bin/waf and
buildtools/wafsamba/wafsamba.py)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13960

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Andrew Bartlett <abartlet@samba.org>