egetopt.c does not use any stdlib.h definations, nor it referenced any

symbol from other module, so remove reference of stdlib.h and extern.h.

Verified with:	md5(1)

usr.bin/pr/egetopt.c

@@ -46,11 +46,8 @@ __FBSDID("$FreeBSD$");
 
 #include <ctype.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
-#include "extern.h"
-
 /*
  * egetopt:	get option letter from argument vector (an extended
  *		version of getopt).