Don't leak DirectSound thread handles

The previous code refrained from calling CloseHandle on
_beingthreadex()-created threads, citing "documentation". Actually the
official docs suggest the exact opposite:

https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/endthread-endthreadex

> when you use _beginthreadex and _endthreadex, you must close the
> thread handle by calling the Win32 CloseHandle API

This means the previous code would leak the thread handle. This can be
confirmed empirically by looking at the process Win32 handle list in
e.g. Process Explorer.

src/hostapi/dsound/pa_win_ds.c

@@ -106,12 +106,10 @@
 
 #if !defined(__CYGWIN__) && !defined(UNDER_CE)
 #define CREATE_THREAD (HANDLE)_beginthreadex
-#undef CLOSE_THREAD_HANDLE /* as per documentation we don't call CloseHandle on a thread created with _beginthreadex */
 #define PA_THREAD_FUNC static unsigned WINAPI
 #define PA_THREAD_ID unsigned
 #else
 #define CREATE_THREAD CreateThread
-#define CLOSE_THREAD_HANDLE CloseHandle
 #define PA_THREAD_FUNC static DWORD WINAPI
 #define PA_THREAD_ID DWORD
 #endif
@@ -3051,9 +3049,7 @@ static PaError StartStream( PaStream *s )
 #ifndef PA_WIN_DS_USE_WMME_TIMER
     if( stream->processingThread )
     {
-#ifdef CLOSE_THREAD_HANDLE
-        CLOSE_THREAD_HANDLE( stream->processingThread ); /* Delete thread. */
-#endif
+        CloseHandle( stream->processingThread ); /* Delete thread. */
         stream->processingThread = NULL;
     }
 #endif
@@ -3092,10 +3088,8 @@ static PaError StopStream( PaStream *s )
         if( WaitForSingleObject( stream->processingThreadCompleted, 30*100 ) == WAIT_TIMEOUT )
             return paUnanticipatedHostError;
 
-#ifdef CLOSE_THREAD_HANDLE
         CloseHandle( stream->processingThread ); /* Delete thread. */
         stream->processingThread = NULL;
-#endif
 
     }
 #endif