AP_GPS: disable esoteric GPS types on FMUv2

libraries/AP_GPS/AP_GPS.cpp

@@ -389,6 +389,9 @@ AP_GPS::detect_instance(uint8_t instance)
             _broadcast_gps_type("u-blox", instance, dstate->current_baud);
             new_gps = new AP_GPS_UBLOX(*this, state[instance], _port[instance]);
         } 
+#if !HAL_MINIMIZE_FEATURES
+        // we drop the MTK drivers when building a small build as they are so rarely used
+        // and are surprisingly large
         else if ((_type[instance] == GPS_TYPE_AUTO || _type[instance] == GPS_TYPE_MTK19) &&
                  AP_GPS_MTK19::_detect(dstate->mtk19_detect_state, data)) {
             _broadcast_gps_type("MTK19", instance, dstate->current_baud);
@@ -399,17 +402,19 @@ AP_GPS::detect_instance(uint8_t instance)
             _broadcast_gps_type("MTK", instance, dstate->current_baud);
             new_gps = new AP_GPS_MTK(*this, state[instance], _port[instance]);
         }
+#endif
         else if ((_type[instance] == GPS_TYPE_AUTO || _type[instance] == GPS_TYPE_SBP) &&
                  AP_GPS_SBP::_detect(dstate->sbp_detect_state, data)) {
             _broadcast_gps_type("SBP", instance, dstate->current_baud);
             new_gps = new AP_GPS_SBP(*this, state[instance], _port[instance]);
         }
-        // save a bit of code space on a 1280
+#if !HAL_MINIMIZE_FEATURES
         else if ((_type[instance] == GPS_TYPE_AUTO || _type[instance] == GPS_TYPE_SIRF) &&
                  AP_GPS_SIRF::_detect(dstate->sirf_detect_state, data)) {
             _broadcast_gps_type("SIRF", instance, dstate->current_baud);
             new_gps = new AP_GPS_SIRF(*this, state[instance], _port[instance]);
         }
+#endif
         else if ((_type[instance] == GPS_TYPE_AUTO || _type[instance] == GPS_TYPE_ERB) &&
                  AP_GPS_ERB::_detect(dstate->erb_detect_state, data)) {
             _broadcast_gps_type("ERB", instance, dstate->current_baud);