McdHandlerMap: simplify logic for incrementing handler-process use counter
McdHandlerMap: simplify logic for incrementing handler-process use counter

In the process, don't leak a copy of the unique name if incrementing from
>= 1.

As suggested during code review.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control