add avr/sleep.h for Teensy3, for Nordic BLE library

teensy3/avr/sleep.h

+#ifndef _AVR_SLEEP_H_
+#define _AVR_SLEEP_H_ 1
+
+#define SLEEP_MODE_IDLE         0
+#define SLEEP_MODE_ADC		0
+#define SLEEP_MODE_PWR_DOWN	1
+#define SLEEP_MODE_PWR_SAVE	1
+#define SLEEP_MODE_STANDBY	1
+#define SLEEP_MODE_EXT_STANDBY	1
+
+#define set_sleep_mode(mode)	// TODO: actually set the mode...
+#define sleep_enable()
+#define sleep_disable()
+#define sleep_cpu()		(asm("wfi"))
+#define sleep_bod_disable()
+#define sleep_mode()		sleep_cpu()
+
+// workaround for early versions of Nordic's BLE library
+#if defined(HAL_ACI_TL_H__) && defined(PLATFORM_H__)
+#define EIMSK uint8_t EIMSKworkaround=0; EIMSKworkaround
+#endif
+
+#endif