Bug#354292: turns out iconv's -t was optional all along

[Dan Jacobson <jidanni@jidanni.org>]

Package: libc6
Version: 2.3.5-8.1
Severity: normal
File: /usr/share/man/man1/iconv.1.gz

On the iconv man page, why don't you please mention that one can leave
off the -t, and it apparently will use LC_something for it, I
discovered by accident, saving us tons of typing over a lifetime.

BTW, SYNOPSIS
       iconv -f encoding -t encoding inputfile
says -t and -f are mandatory, in contrast to
$ iconv -?

I didn't try to see what happens if I don't even give -f.
Maybe it uses the environment too or should.
Anyway, mention it.

Also mention uses of -f X -t X where X is the same, to check a doc is
all in one charset.