DatabaseCampaign: fix log output

When no variants matching the command line parameters were found, the
campaign printed an uninitialized sent_pilots count.

Change-Id: Ib1d70ae86f02059daeb9a62567d6c83802e4986e

src/core/cpn/DatabaseCampaign.hpp

@@ -28,8 +28,6 @@ class DatabaseCampaign : public Campaign {
 
 	void collect_result_thread();
 
-	int sent_pilots;
-
 public:
 	DatabaseCampaign() {};