Remove Dependence on unistd.h and sys/time.h

Summary:
Removed unistd.h and sys/time.h, and refactored getMillisecOfNow() as appeared to be duplicated code.

Compiles with MSVC using craft.

Reviewers: #kde_games, cullmann, aacid

Reviewed By: cullmann, aacid

Subscribers: aacid, cullmann, mlaurent, kde-games-devel

Tags: #kde_games, #craft

Differential Revision: https://phabricator.kde.org/D24583