Be extra careful to only pass the main server config to

ap_find_loaded_module_symbol. Fixes a segfault when using per-module
LogLevel on virtual host scope.

PR: 50117


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1025702 13f79535-47bb-0310-9956-ffa450edef68