ldb: tests for <= and >= integer indexing

ldb: tests for <= and >= integer indexing

Testing max, min and negative values for indexed 32 and 64 bit types.
This has to be done in two different files because the 64 bit type is
LDB_SYNTAX_INTEGER which is implemented at the ldb level, while the 32
bit is added in the ldb-samba module.  Schema syntax binding added for
ldb-samba.

We also need to make sure that full scans are not invoked for LMDB.

Pair-programmed-with: Garming Sam <garming@catalyst.net.nz>

Signed-off-by: Aaron Haslett <aaronhaslett@catalyst.net.nz>
Signed-off-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>