Improve solver channel management according to @aluzzardi comments

Signed-off-by: Tom Chauveau <tom.chauveau@epitech.eu>

client/client.go

@@ -170,26 +170,17 @@ func (c *Client) buildfn(ctx context.Context, st *state.State, env *environment.
 	go catchOutput(buildCh)
 
 	resp, err := c.c.Build(ctx, opts, "", func(ctx context.Context, gw bkgw.Client) (*bkgw.Result, error) {
-		eventsWg := sync.WaitGroup{}
-		closeCh := make(chan *bk.SolveStatus)
+		s := solver.New(solver.Opts{
+			Control: c.c,
+			Gateway: gw,
+			Events:  eventsCh,
+			Auth:    auth,
+			Secrets: secrets,
+			NoCache: c.cfg.NoCache,
+		})
 
 		// Close events channel
-		defer func() {
-			close(closeCh)
-			eventsWg.Wait()
-			close(eventsCh)
-		}()
-
-		s := solver.New(solver.Opts{
-			Control:    c.c,
-			Gateway:    gw,
-			Events:     eventsCh,
-			EventsWg:   &eventsWg,
-			CloseEvent: closeCh,
-			Auth:       auth,
-			Secrets:    secrets,
-			NoCache:    c.cfg.NoCache,
-		})
+		defer s.Stop()
 
 		// Compute output overlay
 		if fn != nil {