crypto/internal/fips140: mark OpenBSD unsupported

Since OpenBSD 7.3, external linking uses -fexecute-only, which breaks
the integrity check. Since we are not validating on OpenBSD anyway,
mark it as unsupported at least for now.

Fixes #70880

Change-Id: I6a6a4656b6c7a97c0962b4158d920f9e6b19678e
Reviewed-on: https://go-review.googlesource.com/c/go/+/639337
Auto-Submit: Filippo Valsorda <[email protected]>
Reviewed-by: Daniel McCarney <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Joel Sing <[email protected]>
Reviewed-by: صادق <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: FiloSottile

src/cmd/dist/test.go

@@ -1812,6 +1812,7 @@ func (t *tester) fipsSupported() bool {
 	case goarch == "wasm",
 		goos == "windows" && goarch == "386",
 		goos == "windows" && goarch == "arm",
+		goos == "openbsd",
 		goos == "aix":
 		return false
 	}

src/crypto/internal/fips140/fips140.go

@@ -46,6 +46,7 @@ func Supported() error {
 	case runtime.GOARCH == "wasm",
 		runtime.GOOS == "windows" && runtime.GOARCH == "386",
 		runtime.GOOS == "windows" && runtime.GOARCH == "arm",
+		runtime.GOOS == "openbsd", // due to -fexecute-only, see #70880
 		runtime.GOOS == "aix":
 		return errors.New("FIPS 140-3 mode is not supported on " + runtime.GOOS + "-" + runtime.GOARCH)
 	}