If both the input and output buffers are exhausted at the same time, return UNDERFLOW as more input data would be required to trigger OVERFLOW.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1522016 13f79535-47bb-0310-9956-ffa450edef68
IE <=9 fixes without the conditional comments

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1522018 13f79535-47bb-0310-9956-ffa450edef68