Add virtual keyword to virtual method override, for clarity

[facchinm]

Moved from arduino/Arduino#5790

eric-wieser commented 22 days ago
These are already treated as virtual by the compiler anyway. Ideally we'd have
the override keyword here too, but I'm not sure if the lcd compiler supports
this.

These are already treated as virtual by the compiler anyway. Ideally we'd have
the override keyword here too, but I'm not sure if the lcd compiler supports
this.

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