cmd/go: adjust BuildInfo.Settings

Make Settings more closely align with command-line flags
and environment variables.

- Change command-line flags to begin with -

- Change syntax of build lines to use Key=Value instead of Key<tab>Value.

- Change CGO_ENABLED to 0/1, matching environment variable,
  instead of false/true.

- Add GOOS and GOARCH.
  These are technically redundant, in that they can be extracted
  from the binary in other ways most of the time, but not always:
  GOOS=ios and GOOS=darwin may produce binaries that are
  difficult to tell apart. In any case, it's a lot easier to have them
  directly in the settings list than derive them from other parts
  of the binary.

- Add GOEXPERIMENT.
  These could be inferred from the tags list, but the experiments
  are being removed from the tags list.

- Change the tags list to match the -tags command-line argument.

- Add msan and race, echoing the -msan and -race arguments
  (always 'true' when present, omitted when false).

- Add GO$GOARCH when set.

Change-Id: Icb59ef4faa5c22407eadd94147b7e53cf4344ce6
Reviewed-on: https://go-review.googlesource.com/c/go/+/358539
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/debug/buildinfo/buildinfo_test.go b/src/debug/buildinfo/buildinfo_test.go
index 44d78a6be0..fd31caf135 100644
--- a/src/debug/buildinfo/buildinfo_test.go
+++ b/src/debug/buildinfo/buildinfo_test.go
@@ -124,7 +124,7 @@ func TestReadFile(t *testing.T) {
 		// build lines are included.
 		got = goVersionRe.ReplaceAllString(got, "go\tGOVERSION\n")
 		got = buildRe.ReplaceAllStringFunc(got, func(match string) string {
-			if strings.HasPrefix(match, "build\tcompiler\t") {
+			if strings.HasPrefix(match, "build\t-compiler=") {
 				return match
 			}
 			return ""
@@ -163,7 +163,7 @@ func TestReadFile(t *testing.T) {
 			want: "go\tGOVERSION\n" +
 				"path\texample.com/m\n" +
 				"mod\texample.com/m\t(devel)\t\n" +
-				"build\tcompiler\tgc\n",
+				"build\t-compiler=gc\n",
 		},
 		{
 			name: "invalid_modules",