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>

3 files changed, 6 insertions, 7 deletions

diff --git a/src/cmd/link/elf_test.go b/src/cmd/link/elf_test.go
index 5037f5b6c0..a75f35bf5d 100644
--- a/src/cmd/link/elf_test.go
+++ b/src/cmd/link/elf_test.go
@@ -10,6 +10,7 @@ package main
 import (
 	"debug/elf"
 	"fmt"
+	"internal/platform"
 	"internal/testenv"
 	"os"
 	"os/exec"
@@ -19,8 +20,6 @@ import (
 	"sync"
 	"testing"
 	"text/template"
-
-	"cmd/internal/sys"
 )
 
 func getCCAndCCFLAGS(t *testing.T, env []string) (string, []string) {
@@ -280,7 +279,7 @@ func TestPIESize(t *testing.T) {
 	// always skip the test if cgo is not supported.
 	testenv.MustHaveCGO(t)
 
-	if !sys.BuildModeSupported(runtime.Compiler, "pie", runtime.GOOS, runtime.GOARCH) {
+	if !platform.BuildModeSupported(runtime.Compiler, "pie", runtime.GOOS, runtime.GOARCH) {
 		t.Skip("-buildmode=pie not supported")
 	}
 
diff --git a/src/cmd/link/internal/ld/config.go b/src/cmd/link/internal/ld/config.go
index 4dd43a16ab..336cb33e3b 100644
--- a/src/cmd/link/internal/ld/config.go
+++ b/src/cmd/link/internal/ld/config.go
@@ -8,6 +8,7 @@ import (
 	"cmd/internal/sys"
 	"fmt"
 	"internal/buildcfg"
+	"internal/platform"
 )
 
 // A BuildMode indicates the sort of object we are building.
@@ -185,7 +186,7 @@ func mustLinkExternal(ctxt *Link) (res bool, reason string) {
 		}()
 	}
 
-	if sys.MustLinkExternal(buildcfg.GOOS, buildcfg.GOARCH) {
+	if platform.MustLinkExternal(buildcfg.GOOS, buildcfg.GOARCH) {
 		return true, fmt.Sprintf("%s/%s requires external linking", buildcfg.GOOS, buildcfg.GOARCH)
 	}
 
diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index c1a30363cb..35babe61fc 100644
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"debug/macho"
 	"internal/buildcfg"
+	"internal/platform"
 	"internal/testenv"
 	"os"
 	"os/exec"
@@ -17,8 +18,6 @@ import (
 	"runtime"
 	"strings"
 	"testing"
-
-	"cmd/internal/sys"
 )
 
 var AuthorPaidByTheColumnInch struct {
@@ -976,7 +975,7 @@ func main() {
 func TestIssue42396(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 
-	if !sys.RaceDetectorSupported(runtime.GOOS, runtime.GOARCH) {
+	if !platform.RaceDetectorSupported(runtime.GOOS, runtime.GOARCH) {
 		t.Skip("no race detector support")
 	}