RFR 8171971: Fix timing bug in JVM management of package export lists

[Alan Bateman]

On 18/01/2017 15:46, harold seigel wrote:
> Hi Alan,
>
> The VM was already lockng the Module_lock during an access check when 
> doing a qualified exports check.  This change expands the scope of the 
> of that lock to also cover checking if the packing is unqualifiedly 
> exported.
I hope it can be looked at again to make it lock-free some day.

>
> Can JVMTI be used to change a package's export state from qualified to 
> unqualified?
No, qualified exports and opens only.

-Alan