Always receiving a BLE count of zero when using Arduino IDE

## Environment :
- Windows 10 (also reproduced on Linux)
- Arduino IDE 1.8.19
- ESP32 espressif arduino boards packages 1.0.6
- T-Beam v1.0 dev board (reproduced on many different other boards)

## Steps to reproduce :
- clone libpax branch master
- edit _lib/libpax/libpax_api.h_ to uncomment build-time options _LIBPAX_WIFI_ and _LIBPAX_BLE_
- copy _lib/libpax_ in arduino libraries folder
- copy the sample program _src/main.cpp_ as _src/main.ino_ and open it in arduino ide
- modify it like this (removing non-arduino version for clarity, and defining _LIBPAX_ARDUINO_ as instructed in README.md) :
```
#define LIBPAX_ARDUINO
#include
#include

struct count_payload_t count_from_libpax;

void process_count(void) {
printf("pax: %d; %d; %d;\n", count_from_libpax.pax, count_from_libpax.wifi_count, count_from_libpax.ble_count);
}

void init() {
struct libpax_config_t configuration;
libpax_default_config(&configuration);
configuration.blecounter = 1;
configuration.blescantime = 0; // infinit
configuration.wificounter = 1;
configuration.wifi_channel_map = WIFI_CHANNEL_ALL;
configuration.wifi_channel_switch_interval = 50;
configuration.wifi_rssi_threshold = -80;
configuration.ble_rssi_threshold = -80;
libpax_update_config(&configuration);

// internal processing initialization
libpax_counter_init(process_count, &count_from_libpax, 10, 1);
libpax_counter_start();
}

void setup() {
init();
}

void loop() {}
```
- build and upload, open the serial monitor.

## Expected output:
Receiving values for both wifi and ble counts.

## Actual output:
16:25:09.268 -> pax: 3; 3; 0;
... 10 minutes later
16:25:19.262 -> pax: 7; 7; 0;
BLE count is always zero.

Note that running the BLE_scan sample sketch included with ESP32 arduino package finds around 15 BLE devices at the same location, same time on the same board.