Fix the long-standing bug that "ab -t10" would loop for 10000 seconds

instead of 10 as documented. Also fix an off-by-one-second error, which
did not matter much (in comparison to the 1000x error ;-)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96073 13f79535-47bb-0310-9956-ffa450edef68