* libmisc/salt.c: Add prototype for l64a(), gensalt(),

* libmisc/salt.c: Add prototype for l64a(), gensalt(),
  SHA_salt_size(), and SHA_salt_rounds().
* libmisc/salt.c: l64a() and gensalt() are static.
* libmisc/salt.c: The `meth' parameter of crypt_make_salt() is a
  const. (ditto for the method variable).
* libmisc/salt.c: SHA_salt_rounds returns a const string.
* libmisc/salt.c: Avoid warnings with cast of random() to double.
* libmisc/salt.c: Replace rand() by random().