go: update to 1.13.1.

Includes a patch from https://go-review.googlesource.com/c/go/+/197602
to try to resolve i686 build failures reported in
https://golang.org/issues/33977.

Closes: #14212 [via git-merge-pr]

srcpkgs/go/patches/gohostarch-bootstrap-fix.patch

@@ -0,0 +1,28 @@
+From e1b1b7856f416ca6ff086adc00adc89fd900992c Mon Sep 17 00:00:00 2001
+From: Brad Fitzpatrick <bradfitz@golang.org>
+Date: Thu, 26 Sep 2019 19:04:00 +0000
+Subject: [PATCH] cmd/dist: fix bootstrap failure when GOHOSTARCH is set
+
+Fixes #33977
+
+Change-Id: I4b136788f08b08c53087af8d3cd56125e620b51b
+Reviewed-on: https://go-review.googlesource.com/c/go/+/197602
+Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
+TryBot-Result: Gobot Gobot <gobot@golang.org>
+Reviewed-by: Cherry Zhang <cherryyz@google.com>
+---
+
+diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
+index f293891..f27ea17 100644
+--- go/src/cmd/dist/buildtool.go
++++ go/src/cmd/dist/buildtool.go
+@@ -250,6 +250,9 @@
+ 	archCaps = fileArch
+ 	fileArch = strings.ToLower(fileArch)
+ 	fileArch = strings.TrimSuffix(fileArch, "splitload")
++	if fileArch == os.Getenv("GOHOSTARCH") {
++		return "", false
++	}
+ 	if fileArch == strings.TrimSuffix(runtime.GOARCH, "le") {
+ 		return "", false
+ 	}

srcpkgs/go/template

@@ -1,6 +1,6 @@
 # Template file for 'go'
 pkgname=go
-version=1.12.8
+version=1.13.1
 revision=1
 create_wrksrc=yes
 build_wrksrc=go
@@ -10,7 +10,7 @@ maintainer="Michael Aldridge <maldridge@voidlinux.org>"
 license="BSD-3-Clause"
 homepage="http://golang.org/"
 distfiles="https://golang.org/dl/go${version}.src.tar.gz"
-checksum=11ad2e2e31ff63fcf8a2bdffbe9bfa2e1845653358daed593c8c2d03453c9898
+checksum=81f154e69544b9fa92b1475ff5f11e64270260d46e7e36c34aafc8bc96209358
 
 nostrip=yes
 noverifyrdeps=yes