components/lwip/apps/sntp: modify SNTP function feature

modify makefile for compile SNTP function in lwip, see sntp file.

components/lwip/Makefile

@@ -4,7 +4,7 @@
 
 COMPONENT_ADD_INCLUDEDIRS := include/lwip include/lwip/port
 
-COMPONENT_SRCDIRS := api apps core/ipv4 core/ipv6 core netif port/freertos port/netif port
+COMPONENT_SRCDIRS := api apps/sntp apps core/ipv4 core/ipv6 core netif port/freertos port/netif port
 
 EXTRA_CFLAGS := -Wno-error=address -Waddress -DLWIP_ESP8266
 

components/lwip/include/lwip/apps/sntp_time.h

@@ -77,6 +77,8 @@ typedef struct{
 }sntp_tm_type;
 
 void sntp_convert_time(sntp_time_t GMT_Time);
-
+bool sntp_set_timezone(s8_t timezone);
+char* sntp_get_real_time(sntp_time_t t);
+u32_t sntp_get_current_timestamp(void);
 #endif