buildtools: fixed broken build with FIPS-enabled host

buildtools: fixed broken build with FIPS-enabled host

MD5 is not supported on FIPS-enabled machines, but the current
work-around is broken. One the other hand, latest Waf has proper
fixup (use sha1 as a replacement to md5) so there is no need for Samba
specific code.

Tested on CentOS-stream-9 with FIPS (Python-3.9.23).

Signed-off-by: Shachar Sharon <ssharon@redhat.com>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>