Merge pull request #107 from mohammadhzp/master

Do not include esp_system.h on nodemcu

impl/random/esp32.h

@@ -1,7 +1,8 @@
 // Important: RF *must* be activated on ESP board
 // https://techtutorialsx.com/2017/12/22/esp32-arduino-random-number-generation/
-
-#include <esp_system.h>
+#ifdef ESP32
+# include <esp_system.h>
+#endif
 
 static int
 hydro_random_init(void)