fix some other MinGW gcc warns

Author: MartinPulec

src/audio/playback/wasapi.cpp

@@ -3,7 +3,7 @@
  * @author Martin Pulec <martin.pulec@cesnet.cz>
  */
 /*
- *  Copyright (c) 2019-2023 CESNET, z. s. p. o.
+ *  Copyright (c) 2019-2026 CESNET, zájmové sružení právnických osob
  *  All rights reserved.
  *
  *  This program is free software: you can redistribute it and/or modify
@@ -102,7 +102,7 @@ string wasapi_get_name(IMMDevice *pDevice); // defined in audio/playback/wasapi.
 static void audio_play_wasapi_probe(struct device_info **available_devices, int *dev_count, void (**deleter)(void *))
 {
         *deleter = free;
-        *available_devices = (struct device_info *) malloc(0);
+        *available_devices = nullptr;
         *dev_count = 0;
 
         IMMDeviceEnumerator *enumerator = nullptr;

src/utils/windows.c

@@ -3,7 +3,7 @@
  * @author Martin Pulec     <pulec@cesnet.cz>
  */
 /*
- * Copyright (c) 2019-2025 CESNET
+ * Copyright (c) 2019-2026 CESNET, zájmové sružení právnických osob
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -277,7 +277,8 @@ get_windows_build()
         typedef NTSTATUS(WINAPI * RtlGetVersionFunc)(
             PRTL_OSVERSIONINFOW lpVersionInformation);
         RtlGetVersionFunc pRtlGetVersion =
-            (RtlGetVersionFunc) GetProcAddress(hNtDll, "RtlGetVersion");
+            (RtlGetVersionFunc) (void *) GetProcAddress(hNtDll,
+                                                        "RtlGetVersion");
         if (pRtlGetVersion == NULL) {
                 MSG(VERBOSE, "Cannot get RtlGetVersion from ntdll.dll!\n");
                 return 0;