fix windows build

Author: methane

Diff for: conncheck.go

@@ -12,16 +12,13 @@
 package mysql
 
 import (
-	"errors"
 	"fmt"
 	"net"
 	"syscall"
 
 	"golang.org/x/sys/unix"
 )
 
-var errUnexpectedEvent = errors.New("recieved unexpected event")
-
 func connCheck(conn net.Conn) error {
 	sysConn, ok := conn.(syscall.Conn)
 	if !ok {

Diff for: packets.go

@@ -14,6 +14,7 @@ import (
 	"database/sql/driver"
 	"encoding/binary"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -101,6 +102,9 @@ func (mc *mysqlConn) readPacket() ([]byte, error) {
 	}
 }
 
+// used in conncheck.go
+var errUnexpectedEvent = errors.New("recieved unexpected event")
+
 // Write packet buffer 'data'
 func (mc *mysqlConn) writePacket(data []byte) error {
 	pktLen := len(data) - 4