libobs: Make get_reg_dword handle missing keys

Previously if the key didn't exist it would return uninitialized stack
memory. Reported at https://obsproject.com/forum/threads/obs-freezes-computer-on-startup-sometimes.78030/#post-330590

libobs/obs-windows.c

@@ -220,17 +220,31 @@ static void log_gaming_features(void)
 			L"AllowAutoGameMode", &game_mode_enabled);
 
 	blog(LOG_INFO, "Windows 10 Gaming Features:");
-	blog(LOG_INFO, "\tGame Bar: %s",
+	if (game_bar_enabled.status == ERROR_SUCCESS) {
+		blog(LOG_INFO, "\tGame Bar: %s",
 			(bool)game_bar_enabled.return_value ? "On" : "Off");
-	blog(LOG_INFO, "\tGame DVR Allowed: %s",
+	}
+
+	if (game_dvr_allowed.status == ERROR_SUCCESS) {
+		blog(LOG_INFO, "\tGame DVR Allowed: %s",
 			(bool)game_dvr_allowed.return_value ? "Yes" : "No");
-	blog(LOG_INFO, "\tGame DVR: %s",
+	}
+
+	if (game_dvr_enabled.status == ERROR_SUCCESS) {
+		blog(LOG_INFO, "\tGame DVR: %s",
 			(bool)game_dvr_enabled.return_value ? "On" : "Off");
-	blog(LOG_INFO, "\tGame DVR Background Recording: %s",
+	}
+
+	if (game_dvr_bg_recording.status == ERROR_SUCCESS) {
+		blog(LOG_INFO, "\tGame DVR Background Recording: %s",
 			(bool)game_dvr_bg_recording.return_value ? "On" :
 			"Off");
-	blog(LOG_INFO, "\tGame Mode: %s",
+	}
+
+	if (game_mode_enabled.status == ERROR_SUCCESS) {
+		blog(LOG_INFO, "\tGame Mode: %s",
 			(bool)game_mode_enabled.return_value ? "On" : "Off");
+	}
 }
 
 void log_system_info(void)

libobs/util/platform-windows.c

@@ -810,8 +810,12 @@ void get_reg_dword(HKEY hkey, LPCWSTR sub_key, LPCWSTR value_name,
 
 	status = RegOpenKeyEx(hkey, sub_key, 0, KEY_READ, &key);
 
-	if (status != ERROR_SUCCESS)
+	if (status != ERROR_SUCCESS) {
+		info->status = status;
+		info->size = 0;
+		info->return_value = 0;
 		return;
+	}
 
 	reg.size = sizeof(reg.return_value);