LU-3775 build: build error with gcc 4.7.0 20110509

LU-3775 build: build error with gcc 4.7.0 20110509

Fixed the error: 'tgt' and 'nf' may be used uninitialized in
this function. Also fixed comparison signed and unsigned
indexes.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I733e3f6456ce2926dfc6f3c5e9ac8f860566c121
Reviewed-on: http://review.whamcloud.com/7382
Tested-by: Hudson
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>