Yet another autogen 5 build error

[Richard Kenner]

I fixed the last problem by adding an include of snprintfv into
getdefs.h but then I get:

top_builddir=.. \
../agen5/autogen -Taginfo -bgetdefs \
        -L ../autoopts -DLEVEL=section \
        ../getdefs/opts.def
ERROR: Unbound variable: down-prog-name
AutoGen ABENDED in template ../autoopts/aginfo.tpl line 61