[loader] diagnostic output

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[rpm] using statefs macros

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
small useful improvements

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[log] only to cerr, no Qt code before core app

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>