Fix prototype of random() and move to stdlib.h

src/include/stdlib.h

@@ -6,6 +6,7 @@ extern void * realloc ( void *old_ptr, size_t new_size );
 extern void * malloc ( size_t size );
 extern void free ( void *ptr );
 extern int system ( const char *command );
+extern long int random ( void );
 
 /**
  * Allocate cleared memory