Make the range test legible; in the process, uncover and close

a bounds overflow condition. [wrowe]
Backports: r417252

Simplify and correctly range test lb_num. [jorton]
Discovered by Hisanobu Okuda
(No prior commit no)

Reviewed by: jorton, wrowe, ylavic



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1799356 13f79535-47bb-0310-9956-ffa450edef68