Remove unneeded headers.

MFC after:	2 weeks

usr.bin/lastcomm/lastcomm.c

@@ -48,8 +48,6 @@ __FBSDID("$FreeBSD$");
 #include <ctype.h>
 #include <err.h>
 #include <errno.h>
-#include <fcntl.h>
-#include <grp.h>
 #include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>

usr.bin/lastcomm/readrec.c

@@ -33,13 +33,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/acct.h>
 
-#include <ctype.h>
-#include <err.h>
 #include <errno.h>
-#include <fcntl.h>
 #include <stddef.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
 int	 readrec_forward(FILE *f, struct acctv2 *av2);