Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56710
Do not perform wrapper mapping if context is being reloaded,
as such mapping is useless and may fail unexpectedly.
Let mapper know that context is being reloaded.

Ignore removeWrapper(), removeWelcomeFile() calls when context is being reloaded,
as that is useless work.
During undeploy the context should have already been unregistered.
During reload the context will be re-registered via addContextVersion().

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1610220 13f79535-47bb-0310-9956-ffa450edef68