[Rivet] plugindemo Makefile

[Hendrik Hoeth]

Thus spake Hendrik Hoeth (hendrik.hoeth at cern.ch):

> in r2274 you added trunk/plugindemo/Makefile to the repository, but
> configure will overwrite that file. Was this intended?

Ignore my mail. I needed to run autoreconf ...

-- 
"Two equal numbers are equivalent, even if they come from two
 different people one of which you don't like"
(MLM about the theoretical top cross-section, in a meeting
about theoretical uncertainties on the top mass)