Patch from Savitha R:

Patch from Savitha R:

    ldap_util
    1. Kdb5_ldap_util interface
    Removed supp enctypes, suppsalttypes from create realm and modify
    realm since they are currently not used
    2. memset passwd strings to zero when not used any more
    3. Using krb5_sname_to_principal in place of gethostbyname while
    creating the kadmin principal with hostname.

    libkdb_ldap
    1. Added mandatory functions which were missing in the LDAP plug-in
    2. Error handling changes - Setting the error message in the
    kerberos context when decryption of the service passwd fails or
    connection to the LDAP server fails during initialization.

Additional changes:

libkdb_ldap: Link against com_err library, to provide error_message().

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@18548 dc483132-0cff-0310-8789-dd5450dbe970