LU-1330 fld: prepare FLD module for client server split

LU-1330 fld: prepare FLD module for client server split

Split FLD server from client, fld_{handler,index}.c are not compliled
unless server support is enabled.  Do not include dt_object.h or
lustre_mdt.h in lustre_fld.h and fix the minor breakages caused by
this elsewhere.  Generally cleanup includes in lustre/fld.

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I60a43934f9aa391689e376f68d249b7244645713
Reviewed-on: http://review.whamcloud.com/2675
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>