[10] Review request for 8074824: Resolve disabled warnings for libawt_xawt

[Semyon Sadetsky]

Hello,

Please review fix for JDK10:

bug:https://bugs.openjdk.java.net/browse/JDK-8074824

webrev: http://cr.openjdk.java.net/~ssadetsky/8074824/webrev.00/

The eliminates gcc warnings produced during compilation of xawt library.

--Semyon