Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54851
Directories without any web.xml fragments should not impact the status of distributable. Patch provided by Trask Stalnaker.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1468415 13f79535-47bb-0310-9956-ffa450edef68