tools/mkwinsyscall: replace deprecated funcs with SyscallN (drops go1.17)

The "syscall.Syscall<number>" functions were deprecated in go1.18 in favor
of the "syscall.SyscallN" function, which does not need the "nargs" argument,
and does not need the list of arguments to be padded with zeros.
https://github.com/golang/go/blob/go1.18/src/syscall/dll_windows.go#L27-L45

Now that go1.17 reached EOL and is no longer maintained, we can update the
code to use the new SyscallN function. This patch updates the mkwinsyscall
utility to generate code using the new SyscallN function, and removes the
utilities that are now redundant.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

internal/socket/zsyscall_windows.go

@@ -21,7 +21,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"sort"
-	"strconv"
 	"strings"
 	"text/template"
 
@@ -541,54 +540,23 @@ func (f *Fn) ParamPrintList() string {
 	return join(f.Params, func(p *Param) string { return fmt.Sprintf(`"%s=", %s, `, p.Name, p.Name) }, `", ", `)
 }
 
-// ParamCount return number of syscall parameters for function f.
-func (f *Fn) ParamCount() int {
-	n := 0
-	for _, p := range f.Params {
-		n += len(p.SyscallArgList())
-	}
-	return n
-}
-
-// SyscallParamCount determines which version of Syscall/Syscall6/Syscall9/...
-// to use. It returns parameter count for correspondent SyscallX function.
-func (f *Fn) SyscallParamCount() int {
-	n := f.ParamCount()
-	switch {
-	case n <= 3:
-		return 3
-	case n <= 6:
-		return 6
-	case n <= 9:
-		return 9
-	case n <= 12:
-		return 12
-	case n <= 15:
-		return 15
-	default:
-		panic("too many arguments to system call")
-	}
-}
-
 // Syscall determines which SyscallX function to use for function f.
 func (f *Fn) Syscall() string {
-	c := f.SyscallParamCount()
-	if c == 3 {
-		return syscalldot() + "Syscall"
-	}
-	return syscalldot() + "Syscall" + strconv.Itoa(c)
+	return syscalldot() + "SyscallN"
 }
 
-// SyscallParamList returns source code for SyscallX parameters for function f.
+// SyscallParamList returns source code for SyscallN parameters for function f,
+// including a leading "comma". If f has no parameters, it returns an empty
+// string.
 func (f *Fn) SyscallParamList() string {
-	a := make([]string, 0)
+	a := make([]string, 0, len(f.Params))
 	for _, p := range f.Params {
 		a = append(a, p.SyscallArgList()...)
 	}
-	for len(a) < f.SyscallParamCount() {
-		a = append(a, "0")
+	if len(a) == 0 {
+		return ""
 	}
-	return strings.Join(a, ", ")
+	return ", " + strings.Join(a, ", ")
 }
 
 // HelperCallParamList returns source code of call into function f helper.
@@ -1045,7 +1013,7 @@ func {{.HelperName}}({{.HelperParamList}}) {{template "results" .}}{
 
 {{define "results"}}{{if .Rets.List}}{{.Rets.List}} {{end}}{{end}}
 
-{{define "syscall"}}{{.Rets.SetReturnValuesCode}}{{.Syscall}}(proc{{.DLLFuncName}}.Addr(), {{.ParamCount}}, {{.SyscallParamList}}){{end}}
+{{define "syscall"}}{{.Rets.SetReturnValuesCode}}{{.Syscall}}(proc{{.DLLFuncName}}.Addr(){{.SyscallParamList}}){{end}}
 
 {{define "tmpvarsreadback"}}{{range .Params}}{{if .TmpVarReadbackCode}}
 {{.TmpVarReadbackCode}}{{end}}{{end}}{{end}}