Electric-pair-mode lets modes choose how to skip whitespace

Electric-pair-mode lets modes choose how to skip whitespace

cc-mode.el-based major-modes with stricter syntax for invalid
NL-terminated strings might choose to have electric-pair-mode skip
some of whitespace into non-string-syntax regions, for the sake of
letting electric-pair-mode chomp that whitespace and make the string
valid again.

* lisp/elec-pair.el (electric-pair-post-self-insert-function): Call it.
(electric-pair-skip-whitespace-function): New buffer-local variable.