fixes ESP32-C3 WiFiProv and btInUse() (espressif#8243)

Author: SuGlider

cores/esp32/esp32-hal-bt.c

@@ -16,7 +16,8 @@
 
 #ifdef CONFIG_BT_ENABLED
 
-bool btInUse(){ return true; }
+// user may want to change it to free resources
+__attribute__((weak)) bool btInUse(){ return true; }
 
 #include "esp_bt.h"
 

cores/esp32/esp32-hal-misc.c

@@ -209,9 +209,8 @@ bool verifyRollbackLater() { return false; }
 #endif
 
 #ifdef CONFIG_BT_ENABLED
-//overwritten in esp32-hal-bt.c
-bool btInUse() __attribute__((weak));
-bool btInUse(){ return false; }
+//from esp32-hal-bt.c
+extern bool btInUse();
 #endif
 
 void initArduino()