cvs-1.11.2: gserver authentication Just Won't Work

"gserver" authentication won't work in cvs-1.11.2, because it attempts
to use the closure of a stdio buffer incorrectly.  Any attempt to use
gserver authentication yields the error message "gserver currently
only enabled for socket connections."

I've attached a diff which fixes this problem and abstracts access to
this information to make it less likely that the problem will occur in
the future.

I've MIME-encoded the diff to protect whitespace.

  jik

diff
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