all: fix some typos

Change-Id: Id4bf4ce8aee8b98baa2f1a9c62a72a9554f7d557
Reviewed-on: https://go-review.googlesource.com/c/sys/+/510595
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>

unix/syscall_internal_darwin_test.go

@@ -18,7 +18,7 @@ func Test_anyToSockaddr_darwin(t *testing.T) {
 		err  error
 	}{
 		{
-			name: "AF_SYSTEM emtpy",
+			name: "AF_SYSTEM empty",
 			rsa:  sockaddrCtlToAny(RawSockaddrCtl{}),
 			err:  EAFNOSUPPORT,
 		},
@@ -51,7 +51,7 @@ func Test_anyToSockaddr_darwin(t *testing.T) {
 			},
 		},
 		{
-			name: "AF_VSOCK emtpy",
+			name: "AF_VSOCK empty",
 			rsa:  sockaddrVMToAny(RawSockaddrVM{}),
 			err:  EAFNOSUPPORT,
 		},