Properly handle use_master in k5_init_creds_get

If we make multiple requests in an initial creds exchange, the
krb5_sendto_kdc call in k5_init_creds_get may flip the use_master
value from 0 to 1 if it detects that the response was from a master
KDC.  Don't turn this into a requirement for future requests during
the same exchange, or we may have trouble following AS referrals.
Reported by Sumit Bose.

ticket: 7650
Link dbtest with libkrb5support

In a static build, linking dbtest could fail on platforms where libdb2
depends on krb5support (platforms without a native mkstemp).  Reported
by Gilles Espinasse <g.esp@free.fr>.

ticket: 7651
Fix warnings in dbtest.c

Check return values of read() and write().  Avoid some unsigned
comparisons.  Cast a ptrdiff_t value to int for use with %d in a
format string.

[ghudson@mit.edu: rewrap long lines; fix one more warning; commit
message]
Document preauth flags for service principals

These flags are overloaded to mean different things for clients and
servers; previously we only documented the client behavior.

ticket: 7653 (new)
tags: pullup
target_version: 1.11.4
Clarify retiring-des based on user feedback

Explain why DES keys should be removed from principals, and clarify
that allow_weak_crypto overrides all other configuration.

ticket: 7654 (new)
tags: pullup
target_version: 1.11.4
Clean up dangling antecedent in allow_weak_crypto

The "previous three lists" are not previous any more.
Say explicitly which three lists, and make the parenthetical bind
to the correct noun.

ticket: 7655 (new)
tags: pullup
target_version: 1.11.4
Fix spurious clock skew caused by preauth delay

Commit 37b0e55e21926c7875b7176e24e13005920915a6 (#7063) prevented
clock skew caused by preauth delay by recording the time of the
initial request.  However, it failed to take into account delay
between requests due to prompting during preauthentication.  Fix this
by recording the request time for each request.

ticket: 7656 (new)
Untabify and reindent t_authpkinit.py