crypto: Fixes for recent Heimdal changes

crypto: Fixes for recent Heimdal changes

The last Heimdal import changed the name of a number of structures
so that they are private to the krb5 code. Mirror this by changing our
prototypes to match the new names.

This solves the key_type problem that we previously fixed by #defining
key_type to hc_key_type, so remove that define.

Change-Id: I9b3f1712b0bf6641a780cc4002e73f8a511ff080
Reviewed-on: http://gerrit.openafs.org/4340
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>