pgsql: Update Emacs configuration

Update Emacs configuration

Update emacs.samples with new configuration snippets that match pgindent
et al. formatting more accurately and follow Emacs Lisp best practices
better.

Add .dir-locals.el with a subset of that configuration for casual
editing and viewing.

Reviewed-by: Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr>
Reviewed-by: Noah Misch <noah(at)leadboat(dot)com>

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/5e3e8e4daaefba47ad7a8b82320531992470b5df

Modified Files
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.dir-locals.el | 18 +++++
src/tools/editors/emacs.samples | 158 +++++++++++++--------------------------
2 files changed, 72 insertions(+), 104 deletions(-)