cmd/cgo/internal/testsanitizers: disable location checking for clang

Pending a resolution to golang#65606, this CL marks clang's ASAN runtime as
unable to symbolize stack traces to unblock the LUCI clang builder.

For golang#65606.
Fixes golang#65469.

Change-Id: I649773085aff30e5703e7f7ac2c72a0430a015c2
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-clang15
Reviewed-on: https://go-review.googlesource.com/c/go/+/562675
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/cgo/internal/testsanitizers/cc_test.go

@@ -16,8 +16,10 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"internal/testenv"
 	"os"
 	"os/exec"
+	"os/user"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -266,12 +268,28 @@ func compilerSupportsLocation() bool {
 	case "gcc":
 		return compiler.major >= 10
 	case "clang":
+		// TODO(65606): The clang toolchain on the LUCI builders is not built against
+		// zlib, the ASAN runtime can't actually symbolize its own stack trace. Once
+		// this is resolved, one way or another, switch this back to 'true'. We still
+		// have coverage from the 'gcc' case above.
+		if inLUCIBuild() {
+			return false
+		}
 		return true
 	default:
 		return false
 	}
 }
 
+// inLUCIBuild returns true if we're currently executing in a LUCI build.
+func inLUCIBuild() bool {
+	u, err := user.Current()
+	if err != nil {
+		return false
+	}
+	return testenv.Builder() != "" && u.Username == "swarming"
+}
+
 // compilerRequiredTsanVersion reports whether the compiler is the version required by Tsan.
 // Only restrictions for ppc64le are known; otherwise return true.
 func compilerRequiredTsanVersion(goos, goarch string) bool {