Windows: skip permissions check on key

This code was attempting to check Linux file permissions
to determine if the key was accessible by other users, which
doesn't work, and therefore prevented users on Windows
to load keys.

Skipping this check on Windows (correspinding tests
were already skipped).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 15d361fd77d69514aa544fbcb5cb7ce15c3184f4)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: e803e487c3f231aa0b35ede630fc388778524969
Component: cli

Author: thaJeztah

components/cli/cli/command/trust/key_load.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"runtime"
 
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
@@ -69,12 +70,14 @@ func loadPrivKey(streams command.Streams, keyPath string, options keyLoadOptions
 }
 
 func getPrivKeyBytesFromPath(keyPath string) ([]byte, error) {
-	fileInfo, err := os.Stat(keyPath)
-	if err != nil {
-		return nil, err
-	}
-	if fileInfo.Mode()&nonOwnerReadWriteMask != 0 {
-		return nil, fmt.Errorf("private key file %s must not be readable or writable by others", keyPath)
+	if runtime.GOOS != "windows" {
+		fileInfo, err := os.Stat(keyPath)
+		if err != nil {
+			return nil, err
+		}
+		if fileInfo.Mode()&nonOwnerReadWriteMask != 0 {
+			return nil, fmt.Errorf("private key file %s must not be readable or writable by others", keyPath)
+		}
 	}
 
 	from, err := os.OpenFile(keyPath, os.O_RDONLY, notary.PrivExecPerms)