[8u] RFR (XS) 8219636: Windows build failure after JDK-8207070 8u backport

[Aleksey Shipilev]

This is 8u-specific bug (build failure):
  https://bugs.openjdk.java.net/browse/JDK-8219636

Fix:

diff -r 3a37ebd8c506 src/windows/classes/sun/awt/windows/WToolkit.java
--- a/src/windows/classes/sun/awt/windows/WToolkit.java Mon Jan 21 19:04:19 2019 -0300
+++ b/src/windows/classes/sun/awt/windows/WToolkit.java Mon Feb 25 12:16:46 2019 +0100
@@ -43,10 +43,11 @@
 import javax.swing.text.JTextComponent;

 import sun.awt.AppContext;
 import sun.awt.AWTAccessor;
 import sun.awt.AWTAutoShutdown;
+import sun.awt.DisplayChangedListener;
 import sun.awt.LightweightFrame;
 import sun.awt.SunToolkit;
 import sun.misc.ThreadGroupUtils;
 import sun.awt.Win32GraphicsDevice;
 import sun.awt.Win32GraphicsEnvironment;

Testing: {Linux,Windows} x86_64 build

Separately: Paul, have you tested the backport patch builds with 8u on Windows?

Let me propose/reiterate the ground rule for requesters: before doing Fix Request, you need to
actually apply the patch, test it, make sure it works, and then Fix Request it, mentioning the
testing you have done and changes you needed to make it work. If the patch touches the OS you don't
have access to, _do not_ take the backport in the works.

Maintainers have to cross-check that testing is adequate for the backport being proposed. Yes, that
is more work, but that is why non-rubber-stamping reviews are needed: they routinely catch simple
mistakes.

-Aleksey