Removed dependency on unistd.h for MSVC in apps
diff --git a/programs/ssl/ssl_fork_server.c b/programs/ssl/ssl_fork_server.c
index 9e30451..76c782b 100644
--- a/programs/ssl/ssl_fork_server.c
+++ b/programs/ssl/ssl_fork_server.c
@@ -34,9 +34,12 @@
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include <unistd.h>
 #include <signal.h>
 
+#if !defined(_MSC_VER)
+#include <unistd.h>
+#endif
+
 #include "polarssl/config.h"
 
 #include "polarssl/entropy.h"