Add blimp to root GN check_targets

blimp/client/feature/settings_feature.h

Index: blimp/client/feature/settings_feature.h
diff --git a/blimp/client/feature/settings_feature.h b/blimp/client/feature/settings_feature.h
index d9e94ef1bd97419592d14c1d9249a7d280209b41..055a7b4c14259d47cdb7f3a67e6f3b5b5adb97e2 100644
--- a/blimp/client/feature/settings_feature.h
+++ b/blimp/client/feature/settings_feature.h
@@ -6,14 +6,13 @@
 #define BLIMP_CLIENT_FEATURE_SETTINGS_FEATURE_H_
 
 #include "base/macros.h"
-#include "blimp/client/blimp_client_export.h"
 #include "blimp/net/blimp_message_processor.h"
 
 namespace blimp {
 namespace client {
 
 // The feature is used to send global settings to the engine.
-class BLIMP_CLIENT_EXPORT SettingsFeature : public BlimpMessageProcessor {
+class SettingsFeature : public BlimpMessageProcessor {
  public:
   SettingsFeature();
   ~SettingsFeature() override;