Fix a problem whereby RewriteMap prg:'s would get out of sync due to

the inappropriate use of nonblocking reads.  Also get rid of the stderr
altogether since mod_rewrite never uses it.

PR: 9534


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96475 13f79535-47bb-0310-9956-ffa450edef68