Improve emacs coding style

Improve emacs coding style

Remove setting of default style, this way is not recommended and
means that all the settings have to be duplicated to demonstrate the
c-add-style method which is a much better way of doing it.

Remove the modified date as it is better stored in SVN.

Tweak a few style parameters to make them conform to the actual LLVM
style.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223765 91177308-0d34-0410-b5e6-96231b3b80d8