keeping the style police happy with vim

By popular demand :), I just added a file llvm/utils/vim/vimrc which you
may use as a starting point for setting up your VIM environment to work
with LLVM coding guidelines, as described in this document:

For (X)Emacs users, I added what I know to llvm/utils/emacs/emacs.el but
I am not sure if that's compatible with both GNU Emacs and XEmacs or if
it needs changes or additions.

Patches welcome.