mmdevice: do not override target Windows version

modules/audio_output/mmdevice.c

@@ -22,8 +22,6 @@
 # include <config.h>
 #endif
 
-#undef _WIN32_WINNT
-#define _WIN32_WINNT 0x600 /* Windows Vista */
 #define INITGUID
 #define COBJMACROS
 #define CONST_VTABLE
@@ -44,6 +42,37 @@ DEFINE_PROPERTYKEY(PKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd,
 #include <vlc_modules.h>
 #include "audio_output/mmdevice.h"
 
+#if (_WIN32_WINNT < 0x600)
+static VOID WINAPI (*InitializeConditionVariable)(PCONDITION_VARIABLE);
+static BOOL WINAPI (*SleepConditionVariableCS)(PCONDITION_VARIABLE,
+                                               PCRITICAL_SECTION, DWORD);
+static VOID WINAPI (*WakeConditionVariable)(PCONDITION_VARIABLE);
+#define LOOKUP(s) \
+    if (((s) = (void *)GetProcAddress(h, #s)) == NULL) return FALSE
+
+BOOL WINAPI DllMain(HINSTANCE, DWORD, LPVOID); /* avoid warning */
+BOOL WINAPI DllMain(HINSTANCE dll, DWORD reason, LPVOID reserved)
+{
+    (void) dll;
+    (void) reserved;
+
+    switch (reason)
+    {
+        case DLL_PROCESS_ATTACH:
+        {
+            HANDLE h = GetModuleHandle(TEXT("kernel32.dll"));
+            if (unlikely(h == NULL))
+                return FALSE;
+            LOOKUP(InitializeConditionVariable);
+            LOOKUP(SleepConditionVariableCS);
+            LOOKUP(WakeConditionVariable);
+            break;
+        }
+    }
+    return TRUE;
+}
+#endif
+
 DEFINE_GUID (GUID_VLC_AUD_OUT, 0x4533f59d, 0x59ee, 0x00c6,
    0xad, 0xb2, 0xc6, 0x8b, 0x50, 0x1a, 0x66, 0x55);