const time.daysPer4Years

4 uses

	time (current package)
		time.go#L919: 	daysPer4Years    = 365*4 + 1
		time.go#L950: 	n = d / daysPer4Years
		time.go#L952: 	d -= daysPer4Years * n
		time.go#L1047: 	d += daysPer4Years * n