There's a tracker about coverage, see
https://bugs.freedesktop.org/show_bug.cgi?id=38840For the moment, no one seemed to be on it (perhaps I'm wrong).
About lcov, I read that it was a frontend to gcov (see
http://gcc.gnu.org/onlinedocs/gcc/Gcov.html) (added a comment on the tracker about this).
It seems quite easy to use for a simple file. Now I don't know how much time one's must invest for a project like LO.
Julien.