make: unifdef for other OSes (undefined)

@@ -49,13 +49,10 @@
 #include <sys/signal.h>         /* SIG_DFL */
 #include <sys/wait.h>           /* wait() */
 
 #include <string.h>             /* strerror() */
 
-#if defined (HP_UX) || defined (linux)
-#include <unistd.h>
-#endif
 
 /*
  * Defined macros
  */
 

@@ -347,32 +344,22 @@
  *              sys_nerr        The size of sys_errlist
  */
 char *
 errmsg(int errnum)
 {
-#ifdef linux
-        return strerror(errnum);
-#else // linux
 
         extern int              sys_nerr;
-#ifdef SUN4_x
-        extern char             *sys_errlist[];
-#endif
         char                    *errbuf;
 
         if ((errnum < 0) || (errnum > sys_nerr)) {
                 errbuf = getmem(6+1+11+1);
                 (void) sprintf(errbuf, catgets(libmksdmsi18n_catd, 1, 127, "Error %d"), errnum);
                 return errbuf;
         } else {
-#ifdef SUN4_x
-                return(sys_errlist[errnum]);
-#endif
                 return strerror(errnum);
 
         }
-#endif // linux
 }
 
 static char static_buf[MAXPATHLEN*3];
 
 /*