Fixed problem on Irix with servers hanging in IdentityCheck,

apparently due to a mismatch between sigaction and setjmp.

Submitted by: Roy Fielding, PR#502
Reviewed by: Jim Jagielski, Randy Terbush, Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@78182 13f79535-47bb-0310-9956-ffa450edef68