waf: disable-python - align tevent wscript

waf: disable-python - align tevent wscript

Drop the configure option for --disable-python as it is now
global in wafsamba.

If samba is set to use a system copy of tevent, and tevent wasn't built
with python support, then the system pytevent will not be found.  If
samba is being built without python support then pytevent is not needed,
so do not bother to try and find it.

Signed-off-by: Ian Stakenvicius <axs@gentoo.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>