monitor: rename *_pop_one to *_pop_any

monitor: rename *_pop_one to *_pop_any

The old names are confusing since both of the old functions are popping
an item from multiple queues rather than a single queue.  In that
sense, *_pop_any() suites better than *_pop_one().

Since at it, touch up the function monitor_qmp_response_pop_any() a bit
to let the callers pass in a QMPResponse struct instead of returning a
struct.  Change the return value to boolean to mark whether we have
popped a valid response instead.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180620073223.31964-3-peterx@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>