Silence FluidSynth's "function is a stub" log messages

[white-axe]

Maruno has complained that FluidSynth now adds useless error messages to the console in Pokémon Essentials, so let's remove them.

[Splendide-Imaginarius]

What is that log message intended for by upstream? Is it indicative of some other issue that we might want to fix?

[white-axe]

The message appears when FluidSynth tries to use two filesystem-related functions, fluid_file_test() that checks whether or not a regular file actually exists at the path where we're trying to open a SoundFont file (to improve errors in the case where the path actually refers to a directory or socket) and fluid_stat() to check if the SoundFont file was modified after FluidSynth's initialization in order to determine whether or not to evict the samples FluidSynth caches in memory, which are not implemented when using -Dosal=embedded. In either case, this functionality is completely unnecessary and the error messages should be debug messages at best.

[Maruno17]

They're debug messages already, appearing in the console upon bootup. The issue is that they'll confuse users, because there's nothing they can do about them - it's a problem FluidSynth is having. It's also clutter because (at least for me) there are 6 messages, which is a lot.

By all means, it'd be better if the problem in FluidSynth was fixed and the messages were never generated to begin with. But if that can't be done, the next best thing is to make sure those messages don't get to the debug console. The messages may say they're errors, but nothing breaks (as far as I'm aware) so they're actually warnings at best. All they're doing is confusing users by telling them something they can't address and which isn't actually causing a problem.

[Splendide-Imaginarius]

@white-axe OK so this is a verbosity bug in FluidSynth's logging (messages are logged at error level when they should be a lower severity)? Is there a FluidSynth issue filed about this?

[white-axe]

Yes, it's an issue with the log level. I don't see any FluidSynth issues for this.

[Splendide-Imaginarius]

@white-axe Would you be willing to file an issue with FluidSynth about this? It seems like the kind of thing that they'd be happy to fix.

[white-axe]

I've opened a pull request for this at FluidSynth/fluidsynth#1795.

[white-axe]

Since FluidSynth 2.5.5 is now released with the log level changed, I've removed the log filtering code in favour of simply bumping FluidSynth from 2.5.0 to 2.5.5.

[Splendide-Imaginarius]

@white-axe Can you squash this PR down to one commit?