Backports: r1102124 (in part, protocol.c only)

Submitted by: sf
Use APR_STATUS_IS_... in some more cases.
While this is not strictly necessary everywhere, it makes it much easier
to find the problematic cases.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x-merge-http-strict@1775697 13f79535-47bb-0310-9956-ffa450edef68