Fixes for new gcc

lib/matejx_avr_lib/mfrc522.c

@@ -18,8 +18,6 @@
 #define SPI_CS_LOW MFRC522_SS_PORT &= ~_BV(MFRC522_SS_BIT)
 #define SPI_CS_HIGH MFRC522_SS_PORT |= _BV(MFRC522_SS_BIT)
 
-static const byte FIFO_SIZE = 64;		// The FIFO is 64 bytes.
-
 void MFRC522_init() {
 	// Set the chipSelectPin as digital output, do not select the slave yet
 	DDR(MFRC522_SS_PORT) |= _BV(MFRC522_SS_BIT);