[12] Review Request: 8212213 All tests for splashscreen stopped worked in jdk12b13

[Sergey Bylokhov]

Hello.
Please review the fix for jdk 12.

Bug: https://bugs.openjdk.java.net/browse/JDK-8211992
Webrev: http://cr.openjdk.java.net/~serb/8211992/webrev.00

This change updates the fix for JDK-8210705[1] and adds one more JNIEXPORT 
which is requires for splashscreen logic.

[1] http://hg.openjdk.java.net/jdk/jdk/rev/8bbb5cbac92c

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Best regards, Sergey.