make: unifdef for other OSes (undefined)

@@ -52,15 +52,11 @@
                 char    *ran_name;      /* symbol defined by */
         }       ran_un;
         off_t   ran_off;                /* library member at this offset */
 };
 
-#if defined(linux)
-#include <ctype.h>              /* isspace */
-#else
 #include <unistd.h>             /* close() */
-#endif
 
 
 /*
  * Defined macros
  */