cmd/dist: fix build failure of misc/cgo/test on arm64

misc/cgo/test fails in 'dist test' on arm64 if the C compiler is of GCC-9.4 or
above and its 'outline atomics' feature is enabled, since the internal linking
hasn't yet supported "__attribute__((constructor))" and also mis-handles hidden
visibility.

This change addresses the problem by skipping the internal linking cases of
misc/cgo/test on linux/arm64. It fixes 'dist test' failure only, user is expected to
pass a GCC option '-mno-outline-atomics' via CGO_CFLAGS if running into the same
problem when building cgo programs using internal linking.

Updates #39466

Change-Id: I57f9e85fca881e5fd2dae6c1b4446bce9e0c1975
Reviewed-on: https://go-review.googlesource.com/c/go/+/262357
Reviewed-by: Cherry Zhang <[email protected]>
Run-TryBot: Cherry Zhang <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Emmanuel Odeke <[email protected]>

Author: shawndx

src/cmd/dist/test.go

@@ -1081,7 +1081,12 @@ func (t *tester) cgoTest(dt *distTest) error {
 	cmd := t.addCmd(dt, "misc/cgo/test", t.goTest())
 	cmd.Env = append(os.Environ(), "GOFLAGS=-ldflags=-linkmode=auto")
 
-	if t.internalLink() {
+	// Skip internal linking cases on arm64 to support GCC-9.4 and above,
+	// only for linux, conservatively.
+	// See issue #39466.
+	skipInternalLink := goarch == "arm64" && goos == "linux"
+
+	if t.internalLink() && !skipInternalLink {
 		cmd := t.addCmd(dt, "misc/cgo/test", t.goTest(), "-tags=internal")
 		cmd.Env = append(os.Environ(), "GOFLAGS=-ldflags=-linkmode=internal")
 	}
@@ -1157,7 +1162,7 @@ func (t *tester) cgoTest(dt *distTest) error {
 
 			if t.supportedBuildmode("pie") {
 				t.addCmd(dt, "misc/cgo/test", t.goTest(), "-buildmode=pie")
-				if t.internalLink() && t.internalLinkPIE() {
+				if t.internalLink() && t.internalLinkPIE() && !skipInternalLink {
 					t.addCmd(dt, "misc/cgo/test", t.goTest(), "-buildmode=pie", "-ldflags=-linkmode=internal", "-tags=internal,internal_pie")
 				}
 				t.addCmd(dt, "misc/cgo/testtls", t.goTest(), "-buildmode=pie")