net: remove unixgram test sockets

Backport https://golang.org/cl/163277 from the master library.

Updates https://gcc.gnu.org/PR89406

Change-Id: I42cea70a7334af725461b2c5b4967a3f1903fa94
Reviewed-on: https://go-review.googlesource.com/c/163200
Reviewed-by: Than McIntosh <thanm@google.com>
3 files changed