fix windows build

util/sys/sys_darwin.go

@@ -7,11 +7,14 @@ import (
 	"encoding/binary"
 	"fmt"
 	"sync"
+	"syscall"
 
 	"github.com/shirou/gopsutil/v4/net"
 	"golang.org/x/sys/unix"
 )
 
+var SIGUSR1 = syscall.SIGUSR1
+
 func GetTCPCount() (int, error) {
 	stats, err := net.Connections("tcp")
 	if err != nil {

util/sys/sys_linux.go

@@ -12,8 +12,11 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"syscall"
 )
 
+var SIGUSR1 = syscall.SIGUSR1
+
 func getLinesNum(filename string) (int, error) {
 	file, err := os.Open(filename)
 	if err != nil {

util/sys/sys_windows.go

@@ -12,6 +12,8 @@ import (
 	"github.com/shirou/gopsutil/v4/net"
 )
 
+var SIGUSR1 = syscall.Signal(0)
+
 // GetConnectionCount returns the number of active connections for the specified protocol ("tcp" or "udp").
 func GetConnectionCount(proto string) (int, error) {
 	if proto != "tcp" && proto != "udp" {