Allow for the possibility of receiving data regardless of the pipe

error condition or receiving EOF on the pipe read. This patch
assumes that a read returning APR_SUCCESS with 0 bytes read is equivalent
to an EOF.

Submitted by:	Dean Gaudet
Reviewed by:	Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@84965 13f79535-47bb-0310-9956-ffa450edef68