Add WinCE support.

* Added two new files: errno.hpp and errno.cpp. They are required to use errno functionality on WM.
* zmq.cpp, msg.h: removed inclusion of errno.h because it is included in zmq.h that is also included by .cpp.
* windows.hpp: process.h is included only for desktop builds.
* thread.cpp: on CE CreateThread is used instead of __beginthreadex
* socket_base.cpp, clock.cpp: on CE include cmnintrin.h instead on intrin.h
* signaler.cpp: on Windows should use special macro around event name (for unicode builds)
* err.hpp: make it include errno.hpp (my file) instead on errno.h when building for CE
* err.cpp: use FormatMessage when building for CE (because CE does not have ANSI API functions)
* zmq.h: do not include errno.h whe building for CE
* libzmq.vcproj: add tro new files

src/msg.cpp

@@ -23,7 +23,6 @@
 #include "../include/zmq.h"
 
 #include <string.h>
-#include <errno.h>
 #include <stdlib.h>
 #include <new>