emacs: make mmm-mode work all the time
emacs: make mmm-mode work all the time

Before this, Latex + Haskell MMM mode only worked for the first buffer
(when doing `emacs FILE.lhs' from the terminal). Subsequent
openings of buffers would not respect the Latex + Haskell MMM mode
system, and Literate Haskell would be used. It seems impossible to
disable literate-hasekll-mode, so we simply make it call latex-mode
in its mode hook.

listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg