Revert "net: skip socket hungry test on iOS"

This reverts commit 3027932ac3.

Reason for revert: It didn't work well enough; a replacement CL that skips external net tests altogether on iOS is coming.

Change-Id: Ib2c5656cee92bcae744f9c99fbcb9f9f2baa0694
Reviewed-on: https://go-review.googlesource.com/113555
Run-TryBot: Elias Naur <elias.naur@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/tcpsock_unix_test.go

@@ -87,11 +87,6 @@ func TestTCPSpuriousConnSetupCompletionWithCancel(t *testing.T) {
 	if testenv.Builder() == "" {
 		testenv.MustHaveExternalNetwork(t)
 	}
-
-	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
-		t.Skip("the iOS limit of 250 open file descriptors is too low")
-	}
-
 	defer dnsWaitGroup.Wait()
 	t.Parallel()
 	const tries = 10000