Hi Vadim,
Another minor datum -- the file contrib.texi had some lines which
had control-M at the end of them (maybe about 10 lines altogether).
I find that if I erase the control-M's and make; make install , then
it appears Maxima / Clisp (English) can find the contrib.info text
(and all the others as well). I have committed contrib.texi sans control-M.
I find that many of the files in doc/info/es/ also contain control-M,
and none of the .texi files outside that directory contain it.
I didn't try to modify anything in doc/info/es/.
hth
Robert Dodier