Infer name type when creating principals

Infer name type when creating principals

In the krb5_parse_name() and krb5_build_principal() families, infer
the name type if the principal is a TGS name or has first component
WELLKNOWN.

Revert commit 0d5df56ea6d4a05c31b7e513ee9ec1542a4b5dce and part of
commit 5994d8928b8ff88751b14bc60c7d7bfce8b30e57 since that
responsibility now lies with krb5_build_principal_ext().

[ghudson@mit.edu: made editorial changes; added removal of
no-longer-needed code; added documentation; rewrote commit message]

ticket: 8983 (new)