libsaria: Include missing header file

This was needed for unlink()

Signed-off-by: Bryan Schumaker <bjschuma@gmail.com>

libsaria/path/dir.cpp

@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <libsaria/path.h>
 
+#include <unistd.h>
 #include <iostream>
 #include <list>
 using namespace std;