Add sleep to glob-file making
Add sleep to glob-file making

This (I hope) closes #17.  It delays running `make` until the present
time is no longer the latest mtime of the .v file; this means that the
machinery will always consider a freshly-made .glob file up-to-date, and
`make` will never consider an out-of-date .glob file new enough.

JasonGross/coq-tools,JasonGross/coq-tools