unix: simplify TestGetwd

No need to use err1 and err2, because there is no mode like in
TestChdirAndGetwd (from os/os_test.go). Also, call fd.Close() via defer.

Change-Id: I8e57acbb382f072c48805f8931c464a169203512
Reviewed-on: https://go-review.googlesource.com/84476
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/syscall_unix_test.go

@@ -383,6 +383,7 @@ func TestGetwd(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Open .: %s", err)
 	}
+	defer fd.Close()
 	// These are chosen carefully not to be symlinks on a Mac
 	// (unlike, say, /var, /etc)
 	dirs := []string{"/", "/usr/bin"}
@@ -406,30 +407,23 @@ func TestGetwd(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Chdir: %v", err)
 		}
-		pwd, err1 := unix.Getwd()
+		pwd, err := unix.Getwd()
+		if err != nil {
+			t.Fatalf("Getwd in %s: %s", d, err)
+		}
 		os.Setenv("PWD", oldwd)
-		err2 := fd.Chdir()
-		if err2 != nil {
+		err = fd.Chdir()
+		if err != nil {
 			// We changed the current directory and cannot go back.
 			// Don't let the tests continue; they'll scribble
 			// all over some other directory.
-			fmt.Fprintf(os.Stderr, "fchdir back to dot failed: %s\n", err2)
+			fmt.Fprintf(os.Stderr, "fchdir back to dot failed: %s\n", err)
 			os.Exit(1)
 		}
-		if err != nil {
-			fd.Close()
-			t.Fatalf("Chdir %s: %s", d, err)
-		}
-		if err1 != nil {
-			fd.Close()
-			t.Fatalf("Getwd in %s: %s", d, err1)
-		}
 		if pwd != d {
-			fd.Close()
 			t.Fatalf("Getwd returned %q want %q", pwd, d)
 		}
 	}
-	fd.Close()
 }
 
 // mktmpfifo creates a temporary FIFO and provides a cleanup function.