poll: Use GetTickCount64 to avoid wraparound issues

[shoelzer]

This replaces PR #993. I was doing that one with the GitHub website but
can't complete it there.

Note that @linquize, @PhilipOakley, and @dscho were having a discussion
about Win XP support and that should conclude before accepting this PR.

From Visual Studio 2015 Code Analysis: Warning C28159 Consider using
'GetTickCount64' instead of 'GetTickCount'.

Reason: GetTickCount overflows roughly every 49 days. Code that does not
take that into account can loop indefinitely. GetTickCount64 operates on
64 bit values and does not have that problem.

Signed-off-by: Steve Hoelzer shoelzer@gmail.com

[dscho]

This replaces PR #993. I was doing that one with the GitHub website but
can't complete it there.

Please note that GitHub created the patch-1 branch in your repository, and you can update the original Pull Request by checking out that branch, modifying it and force-pushing it back.

As to XP support: I will merge this for now, and help @linquize to get XP support back if my question ("Are you this developer?") is answered in the affirmative.

[shoelzer]

@dscho Thanks for the tip. I'm still figuring out GitHub.

[dscho]

@shoelzer no worries.

@linquize I ended up having to add the XP compatibility patch anyways: 8b018c7 (it was necessary because we did not quite yet make the jump away from XP in Git for Windows' source code). It would be good of you if you could react to my comments, otherwise it really feels as if I was talking to your hand.