Stop Logcat spam

[DavidVentura]

As far as I can tell, the logcat spam (cnlohr/rawdrawandroid#21) on Android is caused by calling eglSwapBuffers when the surface is invalid.

This change is not required - I think just bubbling up WindowTermination and asking the user to not call CNFGSwapBuffers on a terminated window is sufficient to stop the spam.

The changes in this PR bubble up the event, but also guard against calls to CNFGSwapBuffers when the window is in an invalid state.

[cnlohr]

Should it just instead handle this internally? It is annoying to ask the user to handle yet another function. Do you know if this could somehow be weakly defined?

[cnlohr]

Hmmmmmm

Do you have any idea if there is a way to handle weak events on function calls in single-file headers?

Maybe we can somehow make the default behavior turn swapbuffers into a deellaaayyyy

[cnlohr]

Ooohhh! Ok, I'll just guard it behind a #define. no worries.

[DavidVentura]

In this case, with the extra guard it's not necessary to have the user handle the event.

Though, calling a no-op in a loop is not great, so it'd be better if the function is not called, and instead handled gracefully, like it is done for Suspend

[cnlohr]

Hmm. I feel like Suspend/Resume is absolutely required. I've currently guarded it behind a #define so only consumers who want it will need to implement it. I really wonder if there's a way of using weak references in header-only libraries