cmd/internal/sys: migrate support.go functions to new internal pkg

Separate out the functions from cmd/internal/sys/support.go and
migrate them to a new package internal/platform, so that functions such as
"RaceDetectorSupported" can be called from tests in std as well as in
cmd. This isn't a complete move of everything in cmd/internal/sys;
there are still many functions left.

The original version of this CL (patch set 1) called the new package
"internal/sys", but for packages that needed both "internal/sys" and
"cmd/internal/sys" the import of the former had to be done with a
different name, which was confusing and also required a hack in
cmd/dist.

Updates #56006.

Change-Id: I866d62e75adbf3a640a06e2c7386a6e9e2a18d91
Reviewed-on: https://go-review.googlesource.com/c/go/+/438475
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>

1 files changed, 0 insertions, 18 deletions

diff --git a/src/cmd/internal/sys/supported_test.go b/src/cmd/internal/sys/supported_test.go
deleted file mode 100644
index 1217814af5..0000000000
--- a/src/cmd/internal/sys/supported_test.go
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package sys
-
-import (
-	"internal/testenv"
-	"runtime"
-	"testing"
-)
-
-func TestMustLinkExternalMatchesTestenv(t *testing.T) {
-	// MustLinkExternal and testenv.CanInternalLink are the exact opposite.
-	if b := MustLinkExternal(runtime.GOOS, runtime.GOARCH); b != !testenv.CanInternalLink() {
-		t.Fatalf("MustLinkExternal() == %v, testenv.CanInternalLink() == %v, don't match", b, testenv.CanInternalLink())
-	}
-}