gdi32: PlgBlt implementation

[Juan Lang]

One more comment on your patch:

>  BOOL WINAPI PlgBlt( HDC hdcDest, const POINT *lpPoint,
> -                        HDC hdcSrc, INT nXDest, INT nYDest, INT nWidth,
> +                        HDC hdcSrc, INT nXSrc, INT nYSrc, INT nWidth,
>                          INT nHeight, HBITMAP hbmMask, INT xMask, INT yMask)
>  {
> -    FIXME("PlgBlt, stub\n");
> -        return 1;
> +    //save actual mode, set GM_ADVANCED
> +    int oldgMode = SetGraphicsMode(hdcDest,GM_ADVANCED);
> +    if (oldgMode == 0)
> +        return FALSE;
> +
> +    //parallelogram coords
> +    POINT plg[3];

Variables must be declared at the beginning of the function.  We
require strict ANSI C.
--Juan