components/lwip,esp32: fixes for C++

- put contents of a few headers into c++ guard blocks
- fix off-by-one error in do_global_ctors
- remove system_init from startup code (should be called from main)

components/tcpip_adapter/include/tcpip_adapter.h

@@ -16,9 +16,7 @@
 #define _TCPIP_ADAPTER_H_
 
 #include <stdint.h>
-
 #include "rom/queue.h"
-
 #include "esp_wifi.h"
 
 #define CONFIG_TCPIP_LWIP 1
@@ -28,6 +26,10 @@
 #include "lwip/ip_addr.h"
 #include "apps/dhcpserver.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define IP2STR(ipaddr) ip4_addr1_16(ipaddr), \
     ip4_addr2_16(ipaddr), \
     ip4_addr3_16(ipaddr), \
@@ -129,5 +131,9 @@ wifi_interface_t tcpip_adapter_get_wifi_if(void *dev);
 esp_err_t tcpip_adapter_get_sta_list(struct station_info *sta_info, struct station_list **sta_list);
 esp_err_t tcpip_adapter_free_sta_list(struct station_list *sta_list);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /*  _TCPIP_ADAPTER_H_ */