waf: Do not install _ldb_text.py if we have system libldb
_ldb_text.py is installed as part of the ldb package and also if you
compile Samba with the system ldb version. This way we have have the
file twice in the same location and run into file confilcts.
This has already been fixed some time ago:
60dc26bfe1573265dcbd87b9dd3439f945e57d97
BUG: https://bugzilla.samba.org/show_bug.cgi?id=12882
Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>
(cherry picked from commit
98e30cf491c63eb0b69c13ad42b720d22944adda)