SDL log functions don't print the priority prefix

[slouken]

Most of the time this is going to be "INFO", and most of the time they're just verbose and not helpful. If someone wants to know more about the priority, they can set a custom log function.

@libsdl-org/a-team, thoughts? Good change? Bad change?

[madebr]

lgtm, perhaps something that needs to be added to the migration docs?

[Kontrabant]

While I don't think that line after line of "INFO" is useful for normal log messages, prefixing errors can be helpful, as you can very easily locate the offending lines by searching for "error" in the console output or a log dump.

I'd say keep the prefixes for warnings and errors.