Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56529
Fix NoSuchElementException while handling attributes with empty string value in custom tags. Based on a patch provided by Hariprasad Manchi. (violetagg/kkolinko)

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc6.0.x/trunk@1595816 13f79535-47bb-0310-9956-ffa450edef68