libgo: define SO_RCVTIMEO on 32-bit GNU/Linux

Fixes golang/go#42872

Change-Id: I509d615b2447008f0e34811c4632ef56a27ea29c
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/273892
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2 files changed