bug#16346: 24.3; electric-pair-mode close-paren issue

[Leo Liu]

In some of the eldoc-documentation-function's when used by
eldoc-post-insert-mode, for example octave-eldoc-function, the eldoc
(calltip) is only shown after inserting the ( and inside the ().

The new feature introduced to electric-pair-mode fails the above by
triggering two successive runs of post-self-insert-hook, one for
inserting the open-paren and the other for the close-paren. Thus the
eldoc message is immediately cleared by the second run.

My impression is if a user didn't type ) it should not trigger
post-self-insert-hook. WDYT?

Leo