ldb: Refuse to build Samba against a newer minor version of ldb

ldb: Refuse to build Samba against a newer minor version of ldb

Samba is not compatible with new versions of ldb (except release versions)

Other users would not notice the breakages, but Samba makes many
more assuptions about the LDB internals than any other package.

(Specifically, LDB 1.2 and 1.4 broke builds against released
Samba versions)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13519

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>