winebuild: Add an "x86_64" flag

[Robert Shearman]

Alexandre Julliard wrote:

>Robert Shearman <rob at codeweavers.com> writes:
>
>  
>
>>ChangeLog:
>>Add an "x86_64" flag in winebuild so we can export 64-bit-only
>>functions in a 64-bit build.
>>    
>>
>
>Are there really enough functions that would need this to justify
>adding a new flag?
>

Get/SetWindowLongPtr in user32, RtlUnwindEx in ntdll, NdrClientCall3 in 
rpcrt4. These are the ones I have noticed so far.

-- 
Rob Shearman