dplayx/tests: Use common wine_dbgstr_guid implementation from test.h.

dlls/dplayx/tests/dplayx.c

@@ -87,8 +87,6 @@ static LPSTR get_temp_buffer(void)
 
 static LPCSTR Guid2str(const GUID *guid)
 {
-    LPSTR buffer = get_temp_buffer();
-
     if (!guid) return "(null)";
 
     /* Service providers */
@@ -124,12 +122,7 @@ static LPCSTR Guid2str(const GUID *guid)
     if (IsEqualGUID(guid, &DPAID_ComPort))
         return "DPAID_ComPort";
 
-    sprintf( buffer, "{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}",
-             guid->Data1, guid->Data2, guid->Data3,
-             guid->Data4[0], guid->Data4[1], guid->Data4[2], guid->Data4[3],
-             guid->Data4[4], guid->Data4[5], guid->Data4[6], guid->Data4[7] );
-    return buffer;
-
+    return wine_dbgstr_guid(guid);
 }