Fix logging `snprintf` with negative time values

[tarek-y-ismail]

mir/src/common/logging/input_timestamp.cpp

Lines 30 to 31 in a3798aa

	snprintf(str, sizeof str, "%lld (%lld.%06lldms ago)",
	when_ns, age_ns / 1000000LL, age_ns % 1000000LL);

The reminder operator preserves the sign age_ns is negative (saw it a couple of times when debugging), so the output can looks something like -1.-500000ms