gcc 7 emits format-truncation warning

[madebr]

When compiling microprofile using gcc 7, a format-truncation warning is emitted at this line: https://github.com/jonasmr/microprofile/blob/bca802bae1e252fde133dff54c47ba8d3a950c1d/microprofile.cpp#L1508 log output: https://travis-ci.com/rwengine/openrw/jobs/161257735#L3033

note: Adding -Wformat-truncation lets all gcc's emit this warning.