lib/talloc: Provide multiple-loading detection for libtalloc via rand()

lib/talloc: Provide multiple-loading detection for libtalloc via rand()

The use of rand() is strongly discrouanged, but here is it ideal, as we just want to select a different
set of random bytes if we are called again within the same process.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Adrian Cochrane <adrianc@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>