ksck: quell build warning
ksck: quell build warning

Was seeing:
../../src/kudu/tools/ksck_checksum.cc:677:1: warning: control reaches end of non-void function [-Wreturn-type]

Change-Id: I696ff790111cc0b371dbb762a3c5167d834136f7
Reviewed-on: http://gerrit.cloudera.org:8080/11661
Reviewed-by: Will Berkeley <c74686ab413a71926fc1bc9d16ebfa30e619336a@gmail.com>
Tested-by: Kudu Jenkins

helifu/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu