The DispmanScreen.c file has a void funtion returning 0l, which obviously shouldn't happen.

It results in a compile error for platforms using this file:

/home/johan/open-jfx/github/jfx/modules/javafx.graphics/src/main/native-glass/monocle/dispman/DispmanScreen.c: In function 'Java_com_sun_glass_ui_monocle_DispmanScreen_wrapNativeSymbols':
/home/johan/open-jfx/github/jfx/modules/javafx.graphics/src/main/native-glass/monocle/dispman/DispmanScreen.c:85:12: error: 'return' with a value, in function returning void [-Werror]
     return 0l;