syscall: fix typo in exec_windows_test.go

nothign -> nothing

Change-Id: I3f5cf20cc094d280f6cafa179eaefd745874dec1
GitHub-Last-Rev: a4cf42f
GitHub-Pull-Request: #45118
Reviewed-on: https://go-review.googlesource.com/c/go/+/303269
Reviewed-by: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: garciaolais

src/syscall/exec_windows_test.go

@@ -52,7 +52,7 @@ func TestChangingProcessParent(t *testing.T) {
 	if os.Getenv("GO_WANT_HELPER_PROCESS") == "parent" {
 		// in parent process
 
-		// Parent does nothign. It is just used as a parent of a child process.
+		// Parent does nothing. It is just used as a parent of a child process.
 		time.Sleep(time.Minute)
 		os.Exit(0)
 	}