[8u] RFR: Backport of JDK-8146238: [macosx] Java2D Queue Flusher crash on OSX after switching between user accounts

[David Alvarez]

Hello Everyone,

I would like to request a review for JDK-8146238, recently added by
Oracle to 8u232 as a BPR.

 JBS Issue: https://bugs.openjdk.java.net/browse/JDK-8146238
 Original change: https://hg.openjdk.java.net/jdk/jdk/rev/07556f8cd819
 Webrev: http://cr.openjdk.java.net/~alvdavi/webrevs/8146238/webrev.8u.00/

Besides the usual quirks, patch did not apply clean due to jdk8u not
having JDK-7188942:
http://hg.openjdk.java.net/jdk10/jdk10/jdk/rev/d278d6b53fcb

Not having this patch caused some changes in the context, but nothing more.

Additionally, src/windows/native/sun/java2d/opengl/WGLSurfaceData.c
required moving some variables to the top of the method declaration to
avoid breaking the build on old versions of Visual Studio.

The patch has passed Tier1 and Tier2 in macosx, linux and windows (x64
for all of them). No new regressions were found.

Thanks,

David