make doc timings

[Han-Wen Nienhuys]

I tried what happens if one concats all texi/tely files together, and
runs lp-book on them.

The result is 25 minutes of purely CPU bound grinding (this is with
Guile 2.2). Then building the remaining docs takes about 15 minutes.
In this last phase, there is some inefficiency: we process the
documents per language directory, but for each directory there is a
bunch of small files, and a humongous notation manual. We can't move
on to the next directory until the notation manual PDF file finishes.

In order to fix this, we would have to reorganize the build system so
it builds everything out of one directory.

-- 
Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen