cntl.h: specify lifetime of logprocs

Change-Id: Id27ac4348a6ad15ad71d85d9fa2cf545b9f0237c
Reviewed-on: http://review.couchbase.org/38386
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>