o add ff lib

o add ff lib samples
o add ff linux sample

tools/ffsample/avr/uart.h

@@ -0,0 +1,4 @@
+void uart_init(void);		/* Initialize UART and Flush FIFOs */
+uint8_t uart_get (void);	/* Get a byte from UART Rx FIFO */
+uint8_t uart_test(void);	/* Check number of data in UART Rx FIFO */
+void uart_put (uint8_t);	/* Put a byte into UART Tx FIFO */