Remove some redundant utility macros.

ATOFFSET in dialog.h became obsolete when the old 'struct Config' gave
way to the new Conf, because its only use was to identify fields in
struct Config for the generic control handlers to update.

And lenof in ssh.h is redundant because there's also a copy in misc.h.
(Which is already included _everywhere_ that lenof is used - I didn't
even need to add any instances of #include "misc.h" after removing the
copy in ssh.h.)

dialog.h

@@ -2,12 +2,6 @@
  * Exports and types from dialog.c.
  */
 
-/*
- * This will come in handy for generic control handlers. Anyone
- * knows how to make this more portable, let me know :-)
- */
-#define ATOFFSET(data, offset) ( (void *) ( (char *)(data) + (offset) ) )
-
 /*
  * This is the big union which defines a single control, of any
  * type.

ssh.h

@@ -190,13 +190,6 @@ void share_setup_x11_channel(ssh_sharing_connstate *cs, share_channel *chan,
 
 Frontend *ssh_get_frontend(Ssh ssh);
 
-/*
- * Useful thing.
- */
-#ifndef lenof
-#define lenof(x) ( (sizeof((x))) / (sizeof(*(x))))
-#endif
-
 #define SSH_CIPHER_IDEA		1
 #define SSH_CIPHER_DES		2
 #define SSH_CIPHER_3DES		3