Cleanup logs in 'make distclean'

Change-Id: Ib05742486183a069334f6fdf12613dbb580e12fe
Reviewed-on: http://review.couchbase.org/28203
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>