Merge branch 'bugfix/cpp_extern_v4.0' into 'release/v4.0'

Add extern C header guards to some files (backport v4.0)

See merge request espressif/esp-idf!8225

components/driver/include/driver/rtc_cntl.h

@@ -18,6 +18,10 @@
 #include "esp_err.h"
 #include "esp_intr_alloc.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @brief Register a handler for specific RTC_CNTL interrupts
  *
@@ -46,3 +50,7 @@ esp_err_t rtc_isr_register(intr_handler_t handler, void* handler_arg,
  *        handler_arg isn't registered
  */
 esp_err_t rtc_isr_deregister(intr_handler_t handler, void* handler_arg);
+
+#ifdef __cplusplus
+}
+#endif

components/esp32/include/esp32/clk.h

@@ -15,6 +15,10 @@
 #pragma once
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @file esp32/clk.h
  *
@@ -85,3 +89,7 @@ int esp_clk_xtal_freq(void);
  * @return Value or RTC counter, expressed in microseconds
  */
 uint64_t esp_clk_rtc_time();
+
+#ifdef __cplusplus
+}
+#endif

components/spi_flash/include/esp_flash_spi_init.h

@@ -17,6 +17,10 @@
 #include "hal/spi_types.h"
 #include "esp_flash.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /// Configurations for the SPI Flash to init
 typedef struct {
     spi_host_device_t host_id;      ///< Bus to use
@@ -53,3 +57,6 @@ esp_err_t spi_bus_add_flash_device(esp_flash_t **out_chip, const esp_flash_spi_d
  */
 esp_err_t spi_bus_remove_flash_device(esp_flash_t *chip);
 
+#ifdef __cplusplus
+}
+#endif