Fix SOCKET_OK test on win64.

Bugfix on 0.2.2.29-beta; partial fix for 4533; found by wanoskarnet

changes/bug4533_part2

@@ -0,0 +1,5 @@
+  o Major bugfixes:
+    - Fix the SOCKET_OK test that we use to tell when socket
+      creation fails so that it works on Win64. Fixes part of bug
+      4533; bugfix on 0.2.2.29-beta. Bug found by wanoskarnet.
+

src/common/compat.h

@@ -396,7 +396,7 @@ typedef int socklen_t;
 
 #ifdef MS_WINDOWS
 #define tor_socket_t intptr_t
-#define SOCKET_OK(s) ((unsigned)(s) != INVALID_SOCKET)
+#define SOCKET_OK(s) ((SOCKET)(s) != INVALID_SOCKET)
 #else
 #define tor_socket_t int
 #define SOCKET_OK(s) ((s) >= 0)