Suggested Runtime change and small Thread fix

[Jeroen Frijters]

Hi,

I would like to move the code to run the shutdown hooks from exit() to a
new method. This allows me to also run the shutdown hooks if the process
termination is triggered by code outside of Java (in my .NET JVM). I
can't see it hurting any other scenarios.

Any objections or comments?

Also fixed Thread.start() to throw IllegalThreadStateException instead
of IllegalStateException.

Regards,
Jeroen

thread.diff
Description: thread.diff

runtime.diff
Description: runtime.diff

changelog.diff
Description: changelog.diff