Foundations now compiles under coq 8.4, patched

This version of Foundations compiles with the following
version of coq 8.4:

https://github.com/DanGrayson/coq/commit/721167c315dba3d57e83cc4a2bc1cdd7b8bef62e

The latest fix to coq was to add a command line option to turn off
sharing.

A convenient way to use the option with proof-general in emacs is to
use LINEFEED to evaluate

   (setq coq-prog-args '("-R" ".." "Foundations" "-no-sharing" "-emacs-U"))

in the buffer *scratch* .