Create (currently failing) test cases for
https://issues.apache.org/bugzilla/show_bug.cgi?id=57252

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1643209 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=57252
Provide application configured error pages with a chance to handle an
async error before the built-in error reporting.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1643210 13f79535-47bb-0310-9956-ffa450edef68
Follow up to r1643002. If something goes wrong, ensure non-container threads are unblocked.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1643216 13f79535-47bb-0310-9956-ffa450edef68
Use the correct constant for the debug message.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1643249 13f79535-47bb-0310-9956-ffa450edef68
Possible fix for https://issues.apache.org/bugzilla/show_bug.cgi?id=57265

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1643270 13f79535-47bb-0310-9956-ffa450edef68