net/http: enable segfaulting test on darwin/arm

Issue #10043 was resolved by https://golang.org/cl/7072.
This test now passes.

Change-Id: I7bdef63d9ee4edcede23613a14a2ddce14018f34
Reviewed-on: https://go-review.googlesource.com/7931Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/transport_test.go

@@ -1788,13 +1788,6 @@ var proxyFromEnvTests = []proxyFromEnvTest{
 }
 
 func TestProxyFromEnvironment(t *testing.T) {
-	if runtime.GOOS == "darwin" && runtime.GOARCH == "arm" {
-		// fmt.Sprintf("%v", (*URL)(nil)) causes a segfault inside the string
-		// method, which lldb intercepts on the darwin/arm builder. Until it
-		// is fixed, skipping the test.
-		t.Skipf("skipping on %s/%s, issue 10043", runtime.GOOS, runtime.GOARCH)
-	}
-
 	ResetProxyEnv()
 	for _, tt := range proxyFromEnvTests {
 		os.Setenv("HTTP_PROXY", tt.env)