Merge r1546835, r1546836 from trunk:

Follow-up to r1546759: Fix compilation when exception hooks aren't enabled.


avoid duplication of APR_HOOK_LINK invocations

Submitted by: trawick
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1588491 13f79535-47bb-0310-9956-ffa450edef68