Bug: Incorrect encoding of complex64 numbers

[hemantjadon]

zap.Complex64 field types incorrectly formats the complex64 numbers. The precision (bitSize) information is lost while converting complex64.
Eg. 2.71+3.14i is formatted as 2.7100000381469727+3.140000104904175i

package main

import (
	"go.uber.org/zap"
)

func main() {
    l, _ := zap.NewProduction()

    l.Info("test", zap.Complex64("key", 2.71+3.14i))
}

Got output

{"level":"info","ts":1257894000,"caller":"sandbox265920417/prog.go:10","msg":"test","key":"2.7100000381469727+3.140000104904175i"}

Expected output

{"level":"info","ts":1257894000,"caller":"sandbox265920417/prog.go:10","msg":"test","key":"2.71+3.14i"}

Reference

https://play.golang.org/p/YH_NmnaRgBs

[hemantjadon]

Reasoning behind this is similar to what was the case in #1002