sd-journal: when picking up a new file, compare inode/device info with...

sd-journal: when picking up a new file, compare inode/device info with previous open file by same name

Let's make sure we aren't confused if a journal file is replaced by a
different one (for example due to rotation) if we are in a q overflow:
let's compare the inode/device information, and if it changed replace
any open file object as needed.

Fixes: #8198