In FluidSynth 2.2.0 an extra state was added to denote stopping. To transition
from this state to a stopped state the rendering needs to be running. Since
04ce1f07 locking was added that skipped the rendering when something else held
a lock, so the state would never get to stopped and join would never return.
In case a character was encoded in multiple bytes, but required fewer bytes to be encoded, the first byte would be copied to the output leaving an invalid Utf8 encoded string. Later uses of the validated string would use the same decode logic, which would yield a question mark and just read a single byte, so nothing dangerous happened.
Furthermore, because the next byte would not be a first byte of an encoded Utf8 character, the last few valid characters could be removed by the validation as well.
An invalid starting year causes all sorts of weird behaviour and crashes in map generation.
Now just set the appropriate setting via IConsoleSetSetting so the validation
and, if needed, clamping is performed on the starting year value.
