trivial: avoid a race condition with platform profile updates
Multiple change events will come in during the course of writing
an updated platform profile. If the daemon responds to both
G_FILE_MONITOR_EVENT_CHANGED
and
G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT
it could potentially race
with the update and read an empty file.
Instead wait until specifically G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT
to update the file.