[Groff] Install pdfpic from Peter Schaffter

[Bernd Warken]

With pdfpic, all .EPS images can also be used even in PDF. When
using .PDFPIC instead of .PSPIC, .EPS graphics are automatically
used within all devices.  A restriction to .PSPIC is quite strange
- .PDFPIC with pdfpic.tmac is a must.

I will need the pdfpic.tmac with .PDFPIC especially for glilypond,
but not yet today.

The macro was written by Peter Schaffter in 2014.  So the license should
be added by the author, as well as the documentation in the man-page
man/groff_tmac.5.man should be improved..

Bernd Warken