heimdal-lib/krb5: keep a copy of config etypes in the context

heimdal-lib/krb5: keep a copy of config etypes in the context

When reading configuration file, keep an extra copy of
the encryption types, and use this when resetting the
encryption types to default.

GSSAPI always resets the enctypes to default before obtaining
a TGS, because the enctypes might have previously altered,
so this prevents changing the etypes from the configured ones
to the full set of supported etypes.

The same patch has gone into upstream heimdal as commit
a3bece1. It is a different solution to the problem fixed
here by commit 1f90983, so this commit will be reverted next
to keep compatibility with uptream.

Signed-off-by: Uri Simchoni <uri@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>