syscall: correct Windows CreateProcess input parameters

Fixes #1718.

R=golang-dev, rsc, peterGo, r
CC=golang-dev
https://golang.org/cl/4435059

src/cmd/gotest/gotest.go

@@ -285,7 +285,7 @@ func doRun(argv []string, returnStdout bool) string {
 			}
 			cmd += `"` + v + `"`
 		}
-		argv = []string{"cmd", "/c", "sh", "-c", cmd}
+		argv = []string{"sh", "-c", cmd}
 	}
 	var err os.Error
 	argv[0], err = exec.LookPath(argv[0])

src/pkg/exec/exec_test.go

@@ -9,19 +9,14 @@ import (
 	"io/ioutil"
 	"testing"
 	"os"
-	"runtime"
 )
 
 func run(argv []string, stdin, stdout, stderr int) (p *Cmd, err os.Error) {
-	if runtime.GOOS == "windows" {
-		argv = append([]string{"cmd", "/c"}, argv...)
-	}
 	exe, err := LookPath(argv[0])
 	if err != nil {
 		return nil, err
 	}
-	p, err = Run(exe, argv, nil, "", stdin, stdout, stderr)
+	return Run(exe, argv, nil, "", stdin, stdout, stderr)
-	return p, err
 }
 
 func TestRunCat(t *testing.T) {

src/pkg/syscall/exec_windows.go

@@ -8,6 +8,7 @@ package syscall
 
 import (
 	"sync"
+	"unsafe"
 	"utf16"
 )
 
@@ -279,7 +280,7 @@ func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid, handle int,
 		}
 	}
 	si := new(StartupInfo)
-	GetStartupInfo(si)
+	si.Cb = uint32(unsafe.Sizeof(*si))
 	si.Flags = STARTF_USESTDHANDLES
 	si.StdInput = fd[0]
 	si.StdOutput = fd[1]