At most a bit of comment of function declaration movement for more
polish. One tricky bit is to #ifdef out (only for gtkdoc of course)
the struct option; forward declaration - gtkdoc needlessly lists it.

FIXME: The struct documentation for igt_helper_process somehow doesn't
get picked up ... Same issue seems to be with the igt_log_level enum,
I've shoveled the relevant documentation into igt_log in free-form for
now.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>