This moves the decoding function that reads the keys from the ber format
into a structure in the common krb5 util code right below the function
that encodes the same data structure into a ber format.
This way the 2 functions are in the same place and can be both used by
all ia components.
Don't use KRB5_PRIVATE.
The patch implements and uses the following krb5 functions that are
otherwise private in recent MIT Kerberos releases:
* krb5_principal2salt_norealm
* krb5_free_ktypes
Signed-off-by: Simo Sorce <ssorce@redhat.com>