d3dx9: Zero constantinfo_reserved on error in get_constants_desc().

Signed-off-by: Paul Gofman <gofmanp@gmail.com>
Signed-off-by: Matteo Bruni <mbruni@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/d3dx9_36/preshader.c

@@ -539,6 +539,8 @@ static HRESULT get_ctab_constant_desc(ID3DXConstantTable *ctab, D3DXHANDLE hc, D
     if (!constant)
     {
         FIXME("Could not get constant desc.\n");
+        if (constantinfo_reserved)
+            *constantinfo_reserved = 0;
         return D3DERR_INVALIDCALL;
     }
     *desc = constant->desc;