[arch-general] /usr/bin/ksh support should be dropped

[Nyuszika7H]

Hi,

I get the following warning when starting up ksh:

WARNING: you should be calling ksh with /bin/ksh,
not with /usr/bin/ksh. Please execute chsh to fix
this. Legacy /usr/bin/ksh support will go away!

$

Considering csh and tcsh were also moved to /bin/, it would be a good idea
to remove the /usr/bin/ksh binary (it exists in /bin/, too).

Note: I'm using zsh as my primary shell, but I installed other shells so
users can use them if they wish.

nyuszika7h