[Groff] Warnings with -mm docs

[Robert Goulding]

The most minimal -mm document, containing a heading:

.HU "This is the heading"
.P
This is a little document.

produces warnings from the fact that DEVTAG-NH and DEVTAG-EO-H are 
undefined, when compiled for devices other than grohtml.  The -mm 
macros need to source devtag.tmac, just as the -ms macros do.  [This is 
using the latest CVS].

--
Robert Goulding
Program in History and Philosophy of Science
University of Notre Dame
Notre Dame IN 46556