[OpenJDK 2D-Dev] RFR(XS): 8213944: Fix AIX build after the removal of Xrandr.h and add a configure check for it

[Volker Simonis]

Hi,

can I please have a review for the following small change:

http://cr.openjdk.java.net/~simonis/webrevs/2018/8213944/
https://bugs.openjdk.java.net/browse/JDK-8213944

Change JDK-8210863 removed the Xrandr.h/randr.h headers from the
OpenJDK sources but forgot to add a configure check for the Xrandr
extension which is now a build dependency.

The change also broke the AIX build. AIX never supported Xrandr, but
that was only detected at runtime, when the JDK was unable to
dynamically load libXrand.so. Now, without Xrandr.h/randr.h in the
source tree any more, we have to conditionally compile some parts of
src/java.desktop/unix/native/libawt_xawt/awt/awt_GraphicsEnv.c such
that it doesn't require the definitions and declarations from
Xrandr.h/randr.h any more.

Thank you and best regards,
Volker