* src/v5.c(v5_alloc_get_init_creds_opt): call the library's struct
init function for the we-malloc-it case.
* src/initopts.c(_pam_krb5_set_init_opts): disable the library's own
change-password-during-get_init_creds behavior, if we're building with
one which lets us disable it, so that we can handle it ourselves.