Solaris wtmp/wtmpx handling

[Steve VanDevender]

It appears to be a pervasive assumption in the Portable OpenSSH code
that wtmp and wtmpx records for the end of a session do not need to
include the user name or hostname.  Unfortunately Solaris appears not to
go along with that assumption; the Solaris "last" command shows all
login sessions initiated by OpenSSH as never terminating, or sometimes
terminating with the user's next login, and examination of wtmp/wtmpx
records for other kinds of logins show that those services do record the
username and hostname in both session start and session end records.

While it looks like it is possible to fix this, it's probably going to
require some extensive code changes and some kind of conditionals to
make this do the right thing in Solaris without changing the behavior on
other OSes.