Fix a silly thinko in exception handing during JavaHL library loading.

* subversion/bindings/javahl/native/jniwrapper/jni_class_cache.cpp
  (ClassCache::create): Explicitly handle the SignalExceptionThrown class.
   Do not use the JNI environment wrapper; we explicitly do not want to know
   about existing exceptions that are currently being thrown.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1545923 13f79535-47bb-0310-9956-ffa450edef68