“Breaking” news
: long after everybody else, I decided to upgrade my Emacs. I started by cloning the Emacs Git repository (in fact, to save download time I did a shallow clone only). I also installed the dependencies needed to compile Emacs (this was sudo apt-get build-dep emacs24 on Ubuntu). Then, I ran make, and that’s it! The only thing left was sudo make install, and everything was working!
Well, almost everything. The only problem I had was with AUCTeX, but I deleted it (using Emacs’ package manager), then installed it again and everything was fine.
IMHO, there are three great things about this. First: the compilation was straightforward, I think I’ll never use ready-made Emacs binaries again. Second: I can now jump to C sources easily. Third: I now have all super-cool stuff the new Emacs (25.0.50.1) gives me, like the possibility of saying (add-hook 'fill-nobreak-predicate #'fill-single-char-nobreak-p) in my init.el (finally!), eww and much more.