Prevent unnecessary "premature end of headers" errors on Win32 by

correctly spotting if a spawned CGI fails, and if so, using the
normal Unix logging to note it. Specifically make the Win32 error return
value from spawn*() of -1 onto the Unix error value of 0 within the
Win32 code.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79417 13f79535-47bb-0310-9956-ffa450edef68