Include windows.h instead of trying to redeclare Sleep os_support.h used to be included in all lavf files, and including windows.h here caused a significant slowdown.
Include windows.h instead of trying to redeclare Sleep
os_support.h used to be included in all lavf files, and including windows.h
here caused a significant slowdown.

git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@12377 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg