Fix invalid memory access (ntop#1596)

We can access `flow->protos` union only after checking the protocol.

Checking `flow->detected_protocol.master_protocol` is redundant because
we already check it in `is_ndpi_proto`

```
AddressSanitizer:DEADLYSIGNAL
=================================================================
==29739==ERROR: AddressSanitizer: SEGV on unknown address 0x000000353820 (pc 0x7f9b64dd2717 bp 0x7fff161a52f0 sp 0x7fff161a4aa8 T0)
==29739==The signal is caused by a READ memory access.
    #0 0x7f9b64dd2717  /build/glibc-SzIz7B/glibc-2.31/string/../sysdeps/x86_64/multiarch/strlen-avx2.S:96
    #1 0x555c65e597d8 in __interceptor_strlen (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader_with_main+0x6407d8) (BuildId: 11ac8ec30f1d49fb0276c9b03368e491505d2bba)
    #2 0x555c65fd85fa in ndpi_strdup /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:269:13
    #3 0x555c65f3e8c6 in process_ndpi_collected_info /home/ivan/svnrepos/nDPI/example/reader_util.c:1188:36
    #4 0x555c65f52cab in packet_processing /home/ivan/svnrepos/nDPI/example/reader_util.c:1567:2
    #5 0x555c65f4b632 in ndpi_workflow_process_packet /home/ivan/svnrepos/nDPI/example/reader_util.c:2110:10
    #6 0x555c65f04d29 in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:109:7
    #7 0x555c65f054bb in main /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:181:17
    ntop#8 0x7f9b64c6e082 in __libc_start_main /build/glibc-SzIz7B/glibc-2.31/csu/../csu/libc-start.c:308:16
    ntop#9 0x555c65e4253d in _start (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader_with_main+0x62953d) (BuildId: 11ac8ec30f1d49fb0276c9b03368e491505d2bba)

```

Found by oss-fuzzer.
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=48020

example/reader_util.c

@@ -1157,10 +1157,12 @@ void process_ndpi_collected_info(struct ndpi_workflow * workflow, struct ndpi_fl
 	     flow->ndpi_flow->protos.ssh.hassh_server);
   }
   /* TLS */
-  else if((is_ndpi_proto(flow, NDPI_PROTOCOL_TLS))
+  else if(is_ndpi_proto(flow, NDPI_PROTOCOL_TLS)
+          || is_ndpi_proto(flow, NDPI_PROTOCOL_DTLS)
+          || is_ndpi_proto(flow, NDPI_PROTOCOL_MAIL_SMTPS)
+          || is_ndpi_proto(flow, NDPI_PROTOCOL_MAIL_IMAPS)
+          || is_ndpi_proto(flow, NDPI_PROTOCOL_MAIL_POPS)
 	  || ((is_quic = is_ndpi_proto(flow, NDPI_PROTOCOL_QUIC)))
-	  || (flow->detected_protocol.master_protocol == NDPI_PROTOCOL_TLS)
-	  || (flow->ndpi_flow->protos.tls_quic.ja3_client[0] != '\0')
 	  ) {
     flow->ssh_tls.ssl_version = flow->ndpi_flow->protos.tls_quic.ssl_version;
 

src/include/ndpi_typedefs.h

@@ -1276,7 +1276,7 @@ struct ndpi_flow_struct {
         char *esni;
       } encrypted_sni;
       ndpi_cipher_weakness server_unsafe_cipher;
-    } tls_quic;
+    } tls_quic; /* Used also by DTLS and POPS/IMAPS/SMTPS */
 
     struct {
       char client_signature[48], server_signature[48];