TLS: fix stack-buffer-overflow

```
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior protocols/tls.c:1812:22
=================================================================
==97754==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ba835bde8e5 at pc 0x557ebb644241 bp 0x7ffec04b0ea0 sp 0x7ffec04b0648
WRITE of size 7 at 0x7ba835bde8e5 thread T0
    #0 0x557ebb644240 in vsnprintf (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x6bf240) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#1 0x557ebb645b1d in snprintf (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x6c0b1d) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#2 0x557ebb749dbc in ndpi_compute_ja4 /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:1812:12
    ntop#3 0x557ebb7445a7 in processClientServerHello /home/ivan/svnrepos/nDPI/src/lib/protocols/tls.c:2946:10
    ntop#4 0x557ebb7073c9 in process_tls /home/ivan/svnrepos/nDPI/src/lib/protocols/quic.c:1397:3
    ntop#5 0x557ebb6ff815 in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data.c:46:7
    ntop#6 0x557ebb602dcb in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x67ddcb) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#7 0x557ebb5ecea8 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x667ea8) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#8 0x557ebb5f299a in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x66d99a) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#9 0x557ebb61c482 in main (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x697482) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
    ntop#10 0x7fa837e27082 in __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:308:16
    ntop#11 0x557ebb5e7b5d in _start (/home/ivan/svnrepos/nDPI/fuzz/fuzz_quic_get_crypto_data+0x662b5d) (BuildId: ce17f7c48055e1f051360bed543c1e18c05f684f)
```

src/lib/protocols/tls.c

@@ -1810,7 +1810,7 @@ static void ndpi_compute_ja4(struct ndpi_detection_module_struct *ndpi_struct,
     if((ja->client.tls_extension[i] > 0) && (ja->client.tls_extension[i] != 0x10 /* ALPN extension */)) {
 #ifdef JA4R_DECIMAL
       rc = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s%u", (num_extn > 0) ? "," : "", ja->client.tls_extension[i]);
-      if(rc > 0) ja4_r_len += rc;
+      if((rc > 0) && (ja4_r_len + rc < JA_STR_LEN)) ja4_r_len += rc; else break;
 #endif
 
       rc = ndpi_snprintf((char *)&tmp_str[tmp_str_len], JA_STR_LEN-tmp_str_len, "%s%04x",