el/dot-emacs.el: Don't prompt to save other buffers on WIP save.

el/dot-emacs.el: Don't prompt to save other buffers on WIP save.

I have `magit-wip-after-save-mode' on, to save my changes into a magic
Git branch while I'm working.  This stimulates a commit on each save,
and Magit is assiduous in asking whether I want to save other buffers
visiting files tracked by the project.  I don't -- and the confirmation
prompt discombobulates me every time it appears.  Tell it this by
advising `magit-wip-commit-buffer-file' appropriately.