[patch ada]: Fix MSG_WAITALL handling for windows native targets

[Arnaud Charlet]

Kai,

Here are Thomas comments on your patch:

--
> Split submitted patch from thread "[patch ada]: Fix issues about
> multilib build of native windows and handle MSG_WAITALL for windows
> native targets"
> into separate ones.
> 
> ChangeLog gcc/ada (ada_wt.txt)
> 
> 2011-03-28  Kai Tietz
> 
> 	* g-socthi-mingw.adb (C_Recvmsg): Handle MSG_WAITALL for
> 	windows native targets.
> 	* s-oscons-tmplt.c (MSG_WAITALL): Define it for native windows
> 	targets to flag value.

>        Fill  : constant Boolean :=
> -                (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
> +                SOSC.MSG_WAITALL /= -1
> +                and then (C.unsigned (Flags) and SOSC.MSG_WAITALL) /= 0;
>        --  Is the MSG_WAITALL flag set? If so we need to fully fill all vectors

Not sure about this. The other change (to s-oscons-tmplt.c) causes
SOSC.MSG_WAITALL to always be defined to 8 in the Windows case, so the
new test against -1 (which would have been relevant without the other
change) now becomes redundant.
     
>  #ifndef MSG_WAITALL
> +#ifdef __MINWGW32__
> +/* We use it on windows native targets, so set to flag value.  */
> +# define MSG_WAITALL (1 << 3)
> +#else

The comment is completely meaningless and should be rewritten. In
particular a note should be added to explain why this will work even
though MSG_WAITALL is not defined in the Winsock header files.