adjust some parents to make the expression a tiny bit clearer and to

make gcc happy

> core.c: In function `core_output_filter':
> core.c:3884: warning: suggest parentheses around && within ||


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97459 13f79535-47bb-0310-9956-ffa450edef68