misc: fix minor bugs (#906)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change

Fix hang when a DLL using the SDK calls `log_fatal` (deadlock)

Fix spicecfg crashing if API server fails to bind (make websocket
teardown conditional)

## Testing

src/spice2x/api/controller.cpp

@@ -93,6 +93,7 @@ Controller::Controller(unsigned short port, std::string password, bool pretty)
     // bind socket to address
     if (bind(this->server, (sockaddr *) &server_address, sizeof(sockaddr)) == -1) {
         log_warning("api", "could not bind socket on port {}: {}", port, get_last_error_string());
+        closesocket(this->server);
         this->server = INVALID_SOCKET;
         if (!cfg::CONFIGURATOR_STANDALONE) {
             log_fatal("api", "failed to start server");
@@ -103,6 +104,7 @@ Controller::Controller(unsigned short port, std::string password, bool pretty)
     // set socket to listen
     if (listen(this->server, server_backlog) == -1) {
         log_warning("api", "could not listen to socket on port {}: {}", port, get_last_error_string());
+        closesocket(this->server);
         this->server = INVALID_SOCKET;
         if (!cfg::CONFIGURATOR_STANDALONE) {
             log_fatal("api", "failed to start server");
@@ -446,7 +448,9 @@ void Controller::free_socket() {
         this->server = INVALID_SOCKET;
     }
 
-    this->websocket->free_socket();
+    if (this->websocket) {
+        this->websocket->free_socket();
+    }
 
     for (auto &s : this->serial) {
         s->free_port();

src/spice2x/api/controller.h

@@ -41,21 +41,21 @@ namespace api {
         bool pretty;
 
         // server
-        WebSocketController *websocket;
+        WebSocketController *websocket = nullptr;
         std::vector<SerialController *> serial;
         std::vector<std::thread> server_workers;
         std::vector<std::thread> server_handlers;
         std::mutex server_handlers_m;
         std::vector<api::ClientState *> client_states;
         std::mutex client_states_m;
-        SOCKET server;
+        SOCKET server = INVALID_SOCKET;
         void server_worker();
         void connection_handler(ClientState client_state);
 
     public:
 
         // state
-        bool server_running;
+        bool server_running = false;
 
         // constructor / destructor
         Controller(unsigned short port, std::string password, bool pretty);

src/spice2x/sdk/sdk.cpp

@@ -225,6 +225,7 @@ sdk_log(
             log_warning(facility_str.c_str(), "{}", message);
             break;
         case SPICE_SDK_LOG_LEVEL_FATAL:
+            lock.unlock();
             log_fatal(facility_str.c_str(), "{}", message);
             break;
         default: