thread: use InitializeCriticalSectionEx if available
thread: use InitializeCriticalSectionEx if available

Windows Vista / Server 2008 and up

Change-Id: I32c5b4e5384d614c5a821ef511293ff014c67966

webmproject/libwebp,redengineer/libwebp,webmproject/libwebp,ttyangf/libwebp,ttyangf/libwebp,ttyangf/libwebp,PKRoma/libwebp,ttyangf/libwebp,redengineer/libwebp,webmproject/libwebp,PKRoma/libwebp,ttyangf/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,redengineer/libwebp,PKRoma/libwebp,redengineer/libwebp,redengineer/libwebp,webmproject/libwebp