All float values defined in the CONFIG_VARIABLE macro seem like they are cast
to at some stage before writing (another issue that needs addressing). The
default value for export-silence-threshold (-INFINITY) is converted to a value
of 0 and as a result nothing is exported with trim enabled.
Use the same fixed silence threshold as Mixbus until proper bounds checking and
GUI is in place.
Related: #6412
Tim Mayberry
6784923a05