fix: Fixing lots of compilation warnings

- fix(esp8266):
  - Adding includes for missing symbols.
  - Removing unused variables.
  - Skip unsupported packing pragmas.
  - Add rom_functions.h for symbols that come from the ESP ROM. Add attributes on
ets_printf so GCC will check the syntax of the formatting string and types of
the arguments.
  - Add ETS_GPIO_INTR_EN(DIS)ABLE macro.
  - Use gpio_output_conf instead of gpio_output_set.

- fix(freertos):
  - Define functions that are useful.
  - Use correct printf symbols when printing.

- fix(lwip):
  - Ignore the warning in sntp.

- fix(mqtt):
  - `xTicksToWait` is unsigned, can't check for less than zero. Remove
unused variables.

- fix(newlib):
  - `_free_r()` returns `void`, not `void *`.
  - Adding includes for missing symbols.

- fix(ssl):
  - Make sure functions always return a value.

Merges https://github.com/espressif/ESP8266_RTOS_SDK/pull/188

components/esp8266/driver/hw_timer.c

@@ -23,6 +23,7 @@
  */
 
 #include "esp_common.h"
+#include "freertos/portmacro.h"
 
 #define US_TO_RTC_TIMER_TICKS(t)          \
     ((t) ?          \

components/esp8266/driver/i2c_master.c

@@ -10,7 +10,9 @@
 *******************************************************************************/
 #include "c_types.h"
 #include "esp8266/ets_sys.h"
+#include "esp_misc.h"
 #include "gpio.h"
+#include "freertos/portmacro.h"
 
 #include "i2c_master.h"
 

components/esp8266/driver/spi_interface.c

@@ -24,6 +24,7 @@
 #include "esp8266/ets_sys.h"
 #include "esp8266/pin_mux_register.h"
 #include "esp_libc.h"
+#include "freertos/portmacro.h"
 //*****************************************************************************
 //
 // Make sure all of the definitions in this header have a C binding.
@@ -457,7 +458,7 @@ int ICACHE_FLASH_ATTR SPIMasterRecvStatus(SpiNum spiNum)
 
     while (READ_PERI_REG(SPI_CMD(spiNum))&SPI_USR);
 
-    uint8_t data = (uint8)(READ_PERI_REG(SPI_W0(spiNum)) & 0xff);
+    (void)(READ_PERI_REG(SPI_W0(spiNum)) & 0xff);
     SHOWREG();
 
     return (uint8)(READ_PERI_REG(SPI_W0(spiNum)) & 0xff);
@@ -520,4 +521,4 @@ void ICACHE_FLASH_ATTR SPIIntClear(SpiNum spiNum)
 
 #ifdef __cplusplus
 }
-#endif
+#endif

components/esp8266/driver/uart.c

@@ -29,6 +29,7 @@
 #include "freertos/queue.h"
 
 #include "uart.h"
+#include "esp8266/rom_functions.h"
 
 enum {
     UART_EVENT_RX_CHAR,
@@ -82,6 +83,7 @@ uart0_write_char(char c)
     }
 }
 
+#if 0
 LOCAL void
 uart_rx_intr_handler_ssc(void *arg)
 {
@@ -109,7 +111,6 @@ uart_rx_intr_handler_ssc(void *arg)
     portEND_SWITCHING_ISR(xHigherPriorityTaskWoken);
 }
 
-#if 0
 LOCAL void
 uart_config(uint8 uart_no, UartDevice *uart)
 {
@@ -149,6 +150,7 @@ uart_config(uint8 uart_no, UartDevice *uart)
 }
 #endif
 
+#if 0
 LOCAL void
 uart_task(void *pvParameters)
 {
@@ -170,7 +172,6 @@ uart_task(void *pvParameters)
     vTaskDelete(NULL);
 }
 
-#if 0
 void
 uart_init(void)
 {
@@ -351,11 +352,9 @@ uart0_rx_intr_handler(void *para)
     /* uart0 and uart1 intr combine togther, when interrupt occur, see reg 0x3ff20020, bit2, bit0 represents
     * uart1 and uart0 respectively
     */
-    uint8 RcvChar;
     uint8 uart_no = UART0;//UartDev.buff_uart_no;
     uint8 fifo_len = 0;
     uint8 buf_idx = 0;
-    uint8 fifo_tmp[128] = {0};
 
     uint32 uart_intr_status = READ_PERI_REG(UART_INT_ST(uart_no)) ;