runtime/cgo: Add initial NetBSD Thread Sanitizer support

Recognize NetBSD in:
 - go/internal/work/init.go
 - race.bash
 - runtime/race/race.go

Add __ps_strings symbol in runtime/cgo/netbsd.go as this is
used internally in the TSan library for NetBSD and used for
ReExec().

Tested on NetBSD/amd64 v. 8.99.12.

Around 98% tests are passing for the ./race.bash target.

Updates #19273

Change-Id: Ic0e48d2fb159a7868aab5e17156eeaca1225e513
GitHub-Last-Rev: d6e082707b9b18df1fe63f723666f4d2eb5e6cfe
GitHub-Pull-Request: golang/go#24322
Reviewed-on: https://go-review.googlesource.com/99835Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/internal/work/init.go

@@ -47,9 +47,9 @@ func instrumentInit() {
 		platform := cfg.Goos + "/" + cfg.Goarch
 		switch platform {
 		default:
-			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
+			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
 			os.Exit(2)
-		case "linux/amd64", "linux/ppc64le", "freebsd/amd64", "darwin/amd64", "windows/amd64":
+		case "linux/amd64", "linux/ppc64le", "freebsd/amd64", "netbsd/amd64", "darwin/amd64", "windows/amd64":
 			// race supported on these platforms
 		}
 	}

src/race.bash

@@ -9,7 +9,7 @@
 set -e
 
 function usage {
-	echo 'race detector is only supported on linux/amd64, linux/ppc64le, freebsd/amd64 and darwin/amd64' 1>&2
+	echo 'race detector is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, netbsd/amd64 and darwin/amd64' 1>&2
 	exit 1
 }
 
@@ -30,6 +30,11 @@ case $(uname) in
 		usage
 	fi
 	;;
+"NetBSD")
+	if [ $(uname -m) != "amd64" ]; then
+		usage
+	fi
+	;;
 *)
 	usage
 	;;

src/runtime/cgo/netbsd.go

@@ -14,6 +14,8 @@ import _ "unsafe" // for go:linkname
 
 //go:linkname _environ environ
 //go:linkname _progname __progname
+//go:linkname ___ps_strings __ps_strings
 
 var _environ uintptr
 var _progname uintptr
+var ___ps_strings uintptr

src/runtime/race/race.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build race,linux,amd64 race,freebsd,amd64 race,darwin,amd64 race,windows,amd64 race,linux,ppc64le
+// +build race,linux,amd64 race,freebsd,amd64 race,netbsd,amd64 race,darwin,amd64 race,windows,amd64 race,linux,ppc64le
 
 package race