bad header doxygen: ap_rflush does not return the number

of bytes flushed, it returns 0 on success, -1 on error.

Should be CTR.

Backport of r1368393 and r1368396 from trunk
resp. r1371930 from 2.2.x.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1371931 13f79535-47bb-0310-9956-ffa450edef68