term: enable TestMakeRawState on darwin/arm64

Go 1.16 renamed the iOS port from darwin/arm64 to ios/arm64 and
darwin/arm64 was repurposed for the macOS ARM64 port (see
https://golang.org/doc/go1.16#darwin).

Now that Go 1.16 is the oldest supported release, the ios tag can be
used exclusively to detect iOS and TestMakeRawState which ought to run
on darwin/arm64 can be enabled on that platform.

For golang/go#45696

Change-Id: Ic51903ea94def1f1144ca74db37533b5c4de8522
Reviewed-on: https://go-review.googlesource.com/c/term/+/352589
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

terminal_test.go

diff --git a/terminal_test.go b/terminal_test.go
index b7766eb..d5c1794 100644
--- a/terminal_test.go
+++ b/terminal_test.go
@@ -407,7 +407,7 @@
 		t.Fatalf("failed to get terminal state from GetState: %s", err)
 	}
 
-	if runtime.GOOS == "ios" || (runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64")) {
+	if runtime.GOOS == "ios" {
 		t.Skip("MakeRaw not allowed on iOS; skipping test")
 	}