[SV 63260] Don't recurse forever if setup_tmpfile() fails

[SV 63260] Don't recurse forever if setup_tmpfile() fails

If we fail during setup_tmpfile() we'll try to write an error, which
will invoke setup_tmpfile() again, etc.  Avoid infinite recursion.
Original patch by Dmitry Goncharov <dgoncharov@users.sf.net>

* src/output.c (setup_tmpfile): Remember we're in this function and
return immediately if we enter it during recursion.
(message): Remember the starting location and use that instead of
fmtbuf.buffer.
(error): Ditto.
(fatal): Ditto.