OSD font setting bugs

[johnnovak]

Bug 1

1. Start WinUAE with the default config.
2. Press Start.
3. F12, Display tab, change to Fullscreen, press OK.
4. F12 again, Misc tab, then open the OSD font dialog, and just close the font dialog by pressing OK (don't even need to change anything).
5. WinUAE crashes and the process disappears without warning.

This happens in both 5.2.0 and 5.3.0

Bug 2

In 5.3.0, in Fullscreen the default OSD font and font size are used, not the ones you set in the OSD font dialog.

In 5.2.0 this works fine.

[johnnovak]

Ping. Minor issue, but it would be worthwhile to fix