Refactor: find_myself to no longer rely on global booth_conf variable
Also, apply the same recursively to both the underlying and superjacent
call graph expansion (respective static functions[*] for the former,
progression up to main.c).
- _find_myself gets marked static as it should have been as of 56801bdcd3e4513948e97947377ce060bc7e1833
Signed-off-by: Jan Pokorný <jpokorny@redhat.com>