passdb: Allow a passdb module to do idmap for everything

passdb: Allow a passdb module to do idmap for everything

This patch seems odd, but the pdb_samba_dsdb module has exactly this
semantics.  That is, the pdb_samba_dsdb is responsible for all IDMAP
values, due to backing on to the idmap.ldb allocator.  This option is
added so we can continue to support the mappings written into that
database even when switching winbindd implementations - the source4/
winbind code would only ask the idmap_ldb code, no matter what the
SID.

Almost all of the behaviour for this is already in winbindd, but we
need this extra flag function so as to avoid (currently intentional)
errors at startup due to not having a per-domain allocation
configured in the smb.conf.

Andrew Bartlett

Change-Id: I6b0d7a1463fe28dfd36715af0285911ecc07585c
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Kamen Mazdrashki <kamenim@samba.org>