Fixed unit tests to compile under MSVC.

1. Including config.h in test.
2. Including windows.h before zippy-test.h.
3. Removed definition of WIN32_LEAN_AND_MEAN. This caused problems in
   build environments that define WIN32_LEAN_AND_MEAN as our
   definition didn't check for prior existence. This constant is old
   and no longer needed anyhow.
4. Disable MSVC warning 4722 since ~LogMessageCrash() never returns.

A=cmumford
R=jeff

snappy-test.cc

@@ -28,13 +28,16 @@
 //
 // Various stubs for the unit tests for the open-source version of Snappy.
 
-#include "snappy-test.h"
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
 
 #ifdef HAVE_WINDOWS_H
-#define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #endif
 
+#include "snappy-test.h"
+
 #include <algorithm>
 
 DEFINE_bool(run_microbenchmarks, true,