policy: fix not selecting better candidate on request

A unset bitmask leads to the candidate selection always return no
candidate, even if there is one.

To select a better candidate regardless of it's classification, provide
a bitmask containing all selection criteria.

Signed-off-by: David Bauer <mail@david-bauer.net>

event.h

@@ -30,6 +30,8 @@ enum uevent_select_reason {
 	UEV_SELECT_REASON_LOAD,
 };
 
+#define UEV_SELECT_REASON_ALL ((1 << UEV_SELECT_REASON_NUM_ASSOC) | (1 << UEV_SELECT_REASON_SIGNAL) | (1 << UEV_SELECT_REASON_LOAD))
+
 struct uevent {
 	enum uevent_type type;
 	enum uevent_reason reason;