Resolve new(er) warnings comparing client_t.protocol with NULL

client_t.protocol is no longer a pointer.

Warnings reported by gcc (Debian 12.2.0-14) 12.2.0

src/sbbs3/filedat.c

@@ -701,7 +701,7 @@ int file_client_hfields(file_t* f, client_t* client)
 		return i;
 	if(*client->host && (i = smb_hfield_str(f, SENDERHOSTNAME, client->host)) != SMB_SUCCESS)
 		return i;
-	if(client->protocol != NULL && (i = smb_hfield_str(f, SENDERPROTOCOL, client->protocol)) != SMB_SUCCESS)
+	if((i = smb_hfield_str(f, SENDERPROTOCOL, client->protocol)) != SMB_SUCCESS)
 		return i;
 	if(client->port) {
 		char	port[16];

src/sbbs3/js_system.c

@@ -1825,7 +1825,6 @@ js_new_user(JSContext *cx, uintN argc, jsval *arglist)
 		}
 	}
 	if(client!=NULL) {
-		if(client->protocol != NULL)
 		SAFECOPY(user.modem,client->protocol);
 		SAFECOPY(user.comp,client->host);
 		SAFECOPY(user.ipaddr,client->addr);

src/sbbs3/postmsg.cpp

@@ -397,7 +397,7 @@ extern "C" int msg_client_hfields(smbmsg_t* msg, client_t* client)
 	if(*client->host
 		&& (i=smb_hfield_str(msg,SENDERHOSTNAME,client->host))!=SMB_SUCCESS)
 		return(i);
-	if(client->protocol!=NULL && (i=smb_hfield_str(msg,SENDERPROTOCOL,client->protocol))!=SMB_SUCCESS)
+	if((i=smb_hfield_str(msg,SENDERPROTOCOL,client->protocol))!=SMB_SUCCESS)
 		return(i);
 	if(client->port) {
 		SAFEPRINTF(port,"%u",client->port);