64-bit build on AIX:

  fix major bogosity in the logic to avoid setting LDR_CNTRL=MAXDATA=xxx
  for a 64-bit build...  the name of the environment variable was wrong
  and even the test usage was bogus


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93743 13f79535-47bb-0310-9956-ffa450edef68