mf: Static dependencies between Metafont files
A glimpse at the history shows that the last change of 'include'
statements has been in 2013, and I'm not even sure here. IMO this
warrants removing the fragile solution to dynamically generate the
dependency files.
Diff:
Passes make, make check and a full make doc.
Patch on countdown for March 19th
Abandoning in favor of https://sourceforge.net/p/testlilyissues/issues/5844/