Merge branch 'idf-4.0-prep' of https://github.com/espressif/arduino-esp32 into idf-release/v4.0

Author: me-no-dev

CMakeLists.txt

@@ -117,7 +117,6 @@ set(COMPONENT_ADD_INCLUDEDIRS
   cores/esp32/
   libraries/ArduinoOTA/src
   libraries/AsyncUDP/src
-  libraries/AzureIoT/src
   libraries/BLE/src
   libraries/BluetoothSerial/src
   libraries/DNSServer/src
@@ -145,12 +144,7 @@ set(COMPONENT_ADD_INCLUDEDIRS
 
 set(COMPONENT_PRIV_INCLUDEDIRS cores/esp32/libb64)
 
-set(COMPONENT_REQUIRES spi_flash mbedtls mdns ethernet esp_adc_cal)
+set(COMPONENT_REQUIRES spi_flash mbedtls mdns esp_adc_cal)
 set(COMPONENT_PRIV_REQUIRES fatfs nvs_flash app_update spiffs bootloader_support openssl bt)
 
 register_component()
-
-set_source_files_properties(libraries/AzureIoT/src/az_iot/iothub_client/src/iothubtransport_mqtt_common.c
-    PROPERTIES COMPILE_FLAGS
-    -Wno-maybe-uninitialized
-)