[PATCH xserver 4/4] os: Use 64-bit tick count on Windows when available

[Jon Turney]

On 27/12/2017 04:10, Jeff Smith wrote:
> On Windows, GetTickCount() returns a value that wraps after 49.7 days.
> Windows Vista and later offer GetTickCount64(), which does not have that
> issue.
> 
> In places that can make use of more than 32 bits from the tick counter,
> use a 64-bit counter if availabile.

Since Vista is EOL, I think we are ok with requiring it, and just 
linking directly with GetTickCount64().

doc/c-extensions should be updated to note the new minimum Windows version.