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/include/driver/gpio.h

@@ -29,6 +29,10 @@
 extern "C" {
 #endif
 #include "esp8266/gpio_register.h"
+
+#define ETS_GPIO_INTR_ENABLE()  _xt_isr_unmask(1 << ETS_GPIO_INUM)
+#define ETS_GPIO_INTR_DISABLE() _xt_isr_mask(1 << ETS_GPIO_INUM)
+
 #define GPIO_Pin_0              (BIT(0))  /* Pin 0 selected */
 #define GPIO_Pin_1              (BIT(1))  /* Pin 1 selected */
 #define GPIO_Pin_2              (BIT(2))  /* Pin 2 selected */

components/esp8266/include/driver/i2c_master.h

@@ -29,16 +29,16 @@
 #endif
 
 #define I2C_MASTER_SDA_HIGH_SCL_HIGH()  \
-    gpio_output_set(1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
+    gpio_output_conf(1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
 
 #define I2C_MASTER_SDA_HIGH_SCL_LOW()  \
-    gpio_output_set(1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
+    gpio_output_conf(1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
 
 #define I2C_MASTER_SDA_LOW_SCL_HIGH()  \
-    gpio_output_set(1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
+    gpio_output_conf(1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
 
 #define I2C_MASTER_SDA_LOW_SCL_LOW()  \
-    gpio_output_set(0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
+    gpio_output_conf(0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
 
 /** \defgroup Driver_APIs Driver APIs
   * @brief Driver APIs

components/esp8266/include/driver/spi_interface.h

@@ -126,8 +126,6 @@ typedef enum
     SpiPinCS_2 = 2,
 } SpiPinCS;
 
-#pragma pack (1)
-
 /**
  * @brief SPI attribute
  */
@@ -152,8 +150,6 @@ typedef struct
     uint8_t     dataLen;        ///< Data byte length.
 } SpiData;
 
-#pragma upack (1)
-
 #define SHOWREG() __ShowRegValue(__func__, __LINE__);
 
 /**
@@ -325,4 +321,4 @@ void SPIIntClear(SpiNum spiNum);
 }
 #endif
 
-#endif //  __SPI_INTERFACE_H__
+#endif //  __SPI_INTERFACE_H__

components/esp8266/include/esp8266/rom_functions.h

@@ -0,0 +1,17 @@
+#ifndef _ROM_FUNCTIONS_H
+#define _ROM_FUNCTIONS_H
+
+#include <stdint.h>
+
+uint32_t Wait_SPI_Idle();
+
+void uart_div_modify(uint32_t uart_no, uint32_t baud_div);
+
+void ets_delay_us(uint32_t us);
+int ets_printf(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+
+void system_soft_wdt_feed();
+
+void Cache_Read_Enable_New();
+
+#endif