wafsamba: the symbol version string of private libraries should be based on the tople...

wafsamba: the symbol version string of private libraries should be based on the toplevel project

If we build a private library all symbols should be made private based
on a unique suffix.

When we use a unique soname and a unique symbol version suffix it's very unlikely
to hit conflicts due to inherited libraries.

For the abi checking we still use the original vnum as abi_vnum.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14780

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