RuntimePermission for explicit GC

[Clemens Eisserer]

> You could pass -XX:+DisableExplicitGC to change System.gc() to a no-
> op. It'll just return without doing anything. This should work in 1.5
> and 1.6.
Furthermore this can completly  confuse diretc-buffer management,
which relies on System.gc(). Thats why I think there should be a
JDK-private API for controlling GC actions with a higher degree of
influence what will happen.

lg Clemens