net: fix inconsistent error values on Accept

This change fixes inconsistent error values on Accept{,TCP,Unix}.

Updates #4856.

Change-Id: Ie3bb534c19a724cacb3ea3f3656e46c810b2123f
Reviewed-on: https://go-review.googlesource.com/8996
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/net/fd_unix.go b/src/net/fd_unix.go
index a7e6d40..329819e 100644
--- a/src/net/fd_unix.go
+++ b/src/net/fd_unix.go
@@ -377,7 +377,7 @@
 	var s int
 	var rsa syscall.Sockaddr
 	if err = fd.pd.PrepareRead(); err != nil {
-		return nil, &OpError{"accept", fd.net, fd.laddr, err}
+		return nil, err
 	}
 	for {
 		s, rsa, err = accept(fd.sysfd)
@@ -391,7 +391,7 @@
 				// before we Accept()ed it; it's a silly error, so try again.
 				continue
 			}
-			return nil, &OpError{"accept", fd.net, fd.laddr, err}
+			return nil, err
 		}
 		break
 	}