[9] Review Request: 8076264 [macosx] Launching app on MacOSX requires enclosing class

[Sergey Bylokhov]

Hello.
Please review the fix for jdk 9.
After the fix we clear all errors caused by getCanonicalName() on the 
mainclass and leave JAVA_MAIN_CLASS_ empty. This empty case will be 
handled in the NSApplicationAWT.m.
Plus small cleanup suggested in the bug report(jstring->jclass).
Bug: https://bugs.openjdk.java.net/browse/JDK-8076264
Webrev can be found at: http://cr.openjdk.java.net/~serb/8076264/webrev.01

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Best regards, Sergey.