certcheck: new field in Android attestation ext

Extra field that is being added for Android U

x509util/android.go

@@ -125,6 +125,7 @@ type AuthorizationList struct {
 	BootPatchlevel            int           `asn1:"optional,explicit,tag:719,default:-1"`
 	DeviceUniqueAttestation   asn1.RawValue `asn1:"optional,explicit,tag:720"`
 	IdentityCredentialKey     asn1.RawValue `asn1:"optional,explicit,tag:721"`
+	AttestationIdSecondImei   []byte        `asn1:"optional,explicit,tag:723"`
 }
 
 // AttestInfoFromCert retrieves and parses an Android attestation information extension
@@ -270,6 +271,7 @@ func showKeyAuthorizations(buf *bytes.Buffer, auths AuthorizationList, prefix st
 	}
 	showNullValue(buf, prefix, "Device Unique Attestation", auths.DeviceUniqueAttestation)
 	showNullValue(buf, prefix, "Identity Credential Key", auths.IdentityCredentialKey)
+	showOptionalHex(buf, prefix, "Attestation Id Second IMEI", auths.AttestationIdSecondImei)
 }
 
 func enumsToString(vals []int, fp func(int) string) string {