Use typedef for SOCKET instead of #define

This makes the code analyzer in CLion happy

Change-Id: Ifa9b99243eb6e63311b0f9a201614ce21af62335
Reviewed-on: http://review.couchbase.org/54296
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>

config.h.in

@@ -50,7 +50,7 @@ typedef long long int64_t;
 #endif
 
 #define closesocket(a) close(a)
-#define SOCKET int
+typedef int SOCKET;
 #define SOCKETPAIR_AF AF_UNIX
 #define SOCKET_ERROR -1
 #define INVALID_SOCKET -1