RFA: Fix the shell used to execute mloop.in

[Frank Ch. Eigler]

> >Is there some reason you can't just hard-code SHELL=/bin/sh in
> >genmloop.sh?
> 
> Because /bin/sh is not the appropriate shell to use on some systems.  (I 
> know for example than on some Solaris machines using /bin/zsh is better).

If the associated shell script not compatible with the unix standard
/bin/sh, perhaps that needs to be fixed.

- FChE