[NSS] ported mozilla upstream changes:

- Bug 1552254 internal_error alert on Certificate Request with sha1+ecdsa in TLS 1.3 (be6a9782)
- Bug 1753535 - Remove obsolete stateEnd check in SEC_ASN1DecoderUpdate. r=rrelyea (800111fa)
- Bug 1756271 - Remove token member from NSSSlot struct. r=rrelyea (55052f78)
- Bug 1396616 - Update nssUTF8_Length to RFC 3629 and fix buffer overrun. r=nss-reviewers,jschanck (2f2c8564)
- Bug 1755264 - TLS 1.3 Illegal legacy_version handling/alerts. r=djackson (7d931c59)
- Bug 1751305 - Remove expired explicitly distrusted certificates from certdata.txt. r=KathleenWilson (b722e523)
- Bug 1751298 - Add Telia Root CA v2 root certificate. r=KathleenWilson (1fcbbd7e)
- Bug 1754890 - Add two D-TRUST 2020 root certificates. r=KathleenWilson (f63fb86d)

security/nss/lib/ssl/ssl.h

@@ -1232,6 +1232,20 @@ NSS_GetClientAuthData(void *arg,
                       struct CERTCertificateStr **pRetCert,
                       struct SECKEYPrivateKeyStr **pRetKey);
 
+/* This function can be called by the appliation's custom GetClientAuthHook
+ * to filter out any certs in the cert list that doesn't match the negotiated
+ * requirements of the current SSL connection.
+ */
+SSL_IMPORT SECStatus
+SSL_FilterClientCertListBySocket(PRFileDesc *socket, CERTCertList *certlist);
+
+/* This function can be called by the application's custom GetClientAuthHook
+ * to determine if a single certificate matches the negotiated requirements of
+ * the current SSL connection.
+ */
+SSL_IMPORT PRBool
+SSL_CertIsUsable(PRFileDesc *socket, CERTCertificate *cert);
+
 /*
 ** Configure DTLS-SRTP (RFC 5764) cipher suite preferences.
 ** Input is a list of ciphers in descending preference order and a length