cmd/dist,internal/platform: temporarily disable race detector on openbsd/amd64

Unfortunately, LLVM TSAN decided to remove OpenBSD support, which
means that the syso files cannot currently be regenerated (see #52090).
The race_openbsd.syso contains a reference to the syscall symbol,
which has been removed from OpenBSD's libc in 7.5. As such, this
means that the race detector no longer works on openbsd/amd64 (at
least until LLVM TSAN support is reinstated for OpenBSD).

Updates #63900

Change-Id: I3474fc43a94e5197815862b7dc420b71d5e08815
Reviewed-on: https://go-review.googlesource.com/c/go/+/582255
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Joel Sing <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: David Chase <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: 4a6f656c

src/cmd/dist/test.go

@@ -1585,7 +1585,7 @@ func raceDetectorSupported(goos, goarch string) bool {
 		return goarch == "amd64" || goarch == "ppc64le" || goarch == "arm64" || goarch == "s390x"
 	case "darwin":
 		return goarch == "amd64" || goarch == "arm64"
-	case "freebsd", "netbsd", "openbsd", "windows":
+	case "freebsd", "netbsd", "windows":
 		return goarch == "amd64"
 	default:
 		return false

src/internal/platform/supported.go

@@ -26,7 +26,7 @@ func RaceDetectorSupported(goos, goarch string) bool {
 		return goarch == "amd64" || goarch == "ppc64le" || goarch == "arm64" || goarch == "s390x"
 	case "darwin":
 		return goarch == "amd64" || goarch == "arm64"
-	case "freebsd", "netbsd", "openbsd", "windows":
+	case "freebsd", "netbsd", "windows":
 		return goarch == "amd64"
 	default:
 		return false