Minor compilation fixes

sw/airborne/peripherals/l3gd20_spi.c

@@ -152,6 +152,7 @@ void l3gd20_spi_event(struct L3gd20_Spi *l3g)
     switch (l3g->spi_trans.status) {
       case SPITransFailed:
         l3g->init_status--; // Retry config (TODO max retry)
+        /* FALLTHROUGH */
       case SPITransSuccess:
         if (l3g->init_status == L3G_CONF_WHO_AM_I_OK) {
           if (l3g->rx_buf[1] == L3GD20_WHO_AM_I) {
@@ -160,6 +161,7 @@ void l3gd20_spi_event(struct L3gd20_Spi *l3g)
             l3g->init_status = L3G_CONF_WHO_AM_I;
           }
         }
+        /* FALLTHROUGH */
       case SPITransDone:
         l3g->spi_trans.status = SPITransDone;
         l3gd20_spi_send_config(l3g);

sw/airborne/subsystems/ahrs/ahrs_vectornav.c

@@ -110,7 +110,7 @@ void ahrs_vectornav_init(void)
   INT32_VECT3_ZERO(ahrs_vn.accel_i);
 
   // initialize data struct
-  memset(&(ahrs_vn.vn_data), sizeof(struct VNData), 0);
+  memset(&(ahrs_vn.vn_data), 0, sizeof(struct VNData));
 
 #if PERIODIC_TELEMETRY
   register_periodic_telemetry(DefaultPeriodic, PPRZ_MSG_ID_VECTORNAV_INFO, send_vn_info);