LU-2675 echo: remove #if 0-ed out regions from echo_client.c

The landing of clio #if 0-ed out some regions of echo_client.c
including what would be the last use of obd_cancel(). Just remove
these regions entirely.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I9c0bf09bd750bbca70ef30cddea25da7c03c6721
Reviewed-on: http://review.whamcloud.com/5580
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>