RFC: AccessController merge

[Andrew Haley]

I'm a bit concerned about efficiency.  For one example: OK, we walk
the stack -- we have to do that -- but we create a string for every
method name , and the only purpose of doing so AFAICS is to compare it
with "doPrivileged".  We then throw away all of those strings we so
laboriously constructed...

I suppose this should go in, but we should study profile data and make
efficiency improvments if required before release.

Andrew.