Merge pull request #289 from jimfcarroll/overflow-clock-use-fix

Fixed potential overflows plus correct use of the system clock.

diff --cc xbmc/Application.cpp
Simple merge

diff --cc xbmc/cores/dvdplayer/DVDDemuxers/DVDDemuxFFmpeg.cpp
Simple merge

diff --cc xbmc/cores/dvdplayer/DVDPlayer.cpp
Simple merge

diff --cc xbmc/input/windows/IRServerSuite.cpp
Simple merge

diff --cc xbmc/rendering/dx/RenderSystemDX.cpp
Simple merge