cmd/compile/internal/importer: correct a matching error

Change-Id: I2499d6ef1df0cc6bf0be8903ce64c03e1f296d19
GitHub-Last-Rev: 1f759d8
GitHub-Pull-Request: #73064
Reviewed-on: https://go-review.googlesource.com/c/go/+/660978
Auto-Submit: Robert Griesemer <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: linsite

src/cmd/compile/internal/importer/gcimporter_test.go

@@ -164,7 +164,7 @@ func TestVersionHandling(t *testing.T) {
 		_, err := Import(make(map[string]*types2.Package), pkgpath, dir, nil)
 		if err != nil {
 			// ok to fail if it fails with a 'not the start of an archive file' error for select files
-			if strings.Contains(err.Error(), "no longer supported") {
+			if strings.Contains(err.Error(), "not the start of an archive file") {
 				switch name {
 				case "test_go1.8_4.a",
 					"test_go1.8_5.a":