ap_get_mime_headers: combine some error paths to remove a conditional

branch from the mainline path.

It might be worthwhile to move all the getline error handling into a
separate function and be a little more i-cache friendly.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97879 13f79535-47bb-0310-9956-ffa450edef68