fixed meshadventurer failing build

variants/meshadventurer/target.h

@@ -11,6 +11,7 @@
 #include <helpers/sensors/LocationProvider.h>
 #ifdef DISPLAY_CLASS
   #include <helpers/ui/SSD1306Display.h>
+  #include <helpers/ui/MomentaryButton.h>
 #endif
 
 class MASensorManager : public SensorManager {
@@ -37,8 +38,10 @@ extern MASensorManager sensors;
 
 #ifdef DISPLAY_CLASS
   extern DISPLAY_CLASS display;
+  extern MomentaryButton user_btn;
 #endif
 
+
 bool radio_init();
 uint32_t radio_get_rng_seed();
 void radio_set_params(float freq, float bw, uint8_t sf, uint8_t cr);