go/internal/gccgoimporter: use t.TempDir() in tests

Use t.TempDir() instead of os.MkdirTemp().

This is a copy of CL 309356 from the main repo.

Updates golang/go#45402.

Change-Id: Ia555a701e4de568871a765ee551e65a5c998cde9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/362246
Trust: Than McIntosh <[email protected]>
Reviewed-by: Bryan C. Mills <[email protected]>

Author: thanm

go/internal/gccgoimporter/importer_test.go

@@ -10,7 +10,6 @@ package gccgoimporter
 
 import (
 	"go/types"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -153,21 +152,11 @@ func TestObjImporter(t *testing.T) {
 	}
 	t.Logf("gccgo version %d.%d", major, minor)
 
-	tmpdir, err := ioutil.TempDir("", "TestObjImporter")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(tmpdir)
-
+	tmpdir := t.TempDir()
 	initmap := make(map[*types.Package]InitData)
 	imp := GetImporter([]string{tmpdir}, initmap)
 
-	artmpdir, err := ioutil.TempDir("", "TestObjImporter")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(artmpdir)
-
+	artmpdir := t.TempDir()
 	arinitmap := make(map[*types.Package]InitData)
 	arimp := GetImporter([]string{artmpdir}, arinitmap)