all: add GOOS=ios

Following CL 254740, this CL does it on x/sys.

Updates golang/go#38485.

Change-Id: I5eab09a9a87c87fc883b5701434415648fb28eb0
Reviewed-on: https://go-review.googlesource.com/c/sys/+/255557
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/unix/syscall_bsd.go b/unix/syscall_bsd.go
index 60bbe10..9ebe92e 100644
--- a/unix/syscall_bsd.go
+++ b/unix/syscall_bsd.go
@@ -272,7 +272,7 @@
 	if err != nil {
 		return
 	}
-	if runtime.GOOS == "darwin" && len == 0 {
+	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && len == 0 {
 		// Accepted socket has no address.
 		// This is likely due to a bug in xnu kernels,
 		// where instead of ECONNABORTED error socket