examples: Remove unused header file.

examples/authentication.c

@@ -18,7 +18,6 @@ clients must be made or how a client should react.
  */
 
 #include <stdio.h>
-#include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
 

examples/knownhosts.c

@@ -20,7 +20,6 @@ clients must be made or how a client should react.
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 
 #include <libssh/libssh.h>

examples/samplesshd.c

@@ -23,7 +23,7 @@ clients must be made or how a client should react.
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
-#include <unistd.h>
+
 #ifndef KEYS_FOLDER
 #ifdef _WIN32
 #define KEYS_FOLDER