Zopen(): FIX crash in error path (since ever!)..
Don't use Fclose() but fclose() on the temporary output file in
the error path since that file is not yet register_file()d at the
time those errors occur!
This error exists since ever, however it is only really, really
dramatical since we do support *file-hook-EXTENSION*. Right??
On the other hand i've used DBGOR() and don't panic but only alert
in the non-debug path, so that users of, e.g., ArchLinux mailx?(1)
only see "Alert: Invalid file pointer" and possibly accept it.
Our poor users!