LU-1214 ptlrpc: removes client lu_target.h/target.c dependency

LU-1214 ptlrpc: removes client lu_target.h/target.c dependency

Needs not include lu_target.h or compile target.c for client.

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Change-Id: I332864158839a8ed1f1df3b24477f5e68ef4ecb7
Reviewed-on: http://review.whamcloud.com/2362
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>