LU-2886 obdclass: remove obsoleted md_local_file.c

This library is not used anymore and is replaced by
local_storage.c. Patch removed last remnants of it.

Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: I4d1371908db898efc8c5cd650357c449f369f51b
Reviewed-on: http://review.whamcloud.com/6107
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>