new file:   base/os/Makefile
	new file:   base/os/condition.cc
	new file:   base/os/condition.h
	new file:   base/os/lock.cc
	new file:   base/os/lock.h
	new file:   base/os/md5.cc
	new file:   base/os/md5.h
	new file:   base/os/mutex.cc
	new file:   base/os/mutex.h
	new file:   base/os/singleton.cc
	new file:   base/os/singleton.h
	new file:   base/os/thread_base.cc
	new file:   base/os/thread_base.h