lwip/linux: Add lwip support for networking component under linux

linux/lwip: Wrap some IO posix functions
* to workaourd the FreeRTOS EINTR issue (when building without lwip)
* to correctly choose the sub-system based on fd (when building with
lwip) -- passing control to either linux/system or to lwip
This commit also addapts tapio-if to provide DHCP client by default and
configurable settings for static IP

examples/protocols/esp_http_client/main/CMakeLists.txt

@@ -3,7 +3,7 @@
 # (If this was a component, we would set COMPONENT_EMBED_TXTFILES here.)
 set(requires "")
 if(${IDF_TARGET} STREQUAL "linux")
-    list(APPEND requires esp_stubs esp-tls esp_http_client protocol_examples_common nvs_flash)
+    list(APPEND requires esp_stubs esp_event esp-tls esp_http_client protocol_examples_common nvs_flash)
 endif()
 idf_component_register(SRCS "esp_http_client_example.c"
                     INCLUDE_DIRS "."

examples/protocols/esp_http_client/main/esp_http_client_example.c

@@ -22,11 +22,9 @@
 #include "esp_crt_bundle.h"
 #endif
 
-#if !CONFIG_IDF_TARGET_LINUX
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "esp_system.h"
-#endif
 
 #include "esp_http_client.h"