Update IDF to ebdcbe8c6 (#2539)

- ESP-Face to 2937054
- ESP32-Camera to 113629b

tools/sdk/include/vfs/esp_vfs.h

@@ -1,4 +1,4 @@
-// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/termios.h>
+#include <sys/poll.h>
 #include <dirent.h>
 #include <string.h>
 #include "sdkconfig.h"
@@ -385,6 +386,22 @@ void esp_vfs_select_triggered(SemaphoreHandle_t *signal_sem);
  */
 void esp_vfs_select_triggered_isr(SemaphoreHandle_t *signal_sem, BaseType_t *woken);
 
+/**
+ * @brief Implements the VFS layer for synchronous I/O multiplexing by poll()
+ *
+ * The implementation is based on esp_vfs_select. The parameters and return values are compatible with POSIX poll().
+ *
+ * @param fds         Pointer to the array containing file descriptors and events poll() should consider.
+ * @param nfds        Number of items in the array fds.
+ * @param timeout     Poll() should wait at least timeout milliseconds. If the value is 0 then it should return
+ *                    immediately. If the value is -1 then it should wait (block) until the event occurs.
+ *
+ * @return            A positive return value indicates the number of file descriptors that have been selected. The 0
+ *                    return value indicates a timed-out poll. -1 is return on failure and errno is set accordingly.
+ *
+ */
+int esp_vfs_poll(struct pollfd *fds, nfds_t nfds, int timeout);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif