Add more include protection macros to give the user warnings when they try to manually include private driver header files, instead of the public driver headers.

LUFA/Drivers/Peripheral/SerialStream.h

@@ -70,7 +70,7 @@
 			extern FILE USARTStream;
 
 		/* Function Prototypes: */
-		#if defined(INCLUDE_FROM_SERIALSTREAM_C)
+		#if defined(__INCLUDE_FROM_SERIALSTREAM_C)
 			static int SerialStream_TxByte(char DataByte, FILE *Stream) ATTR_NON_NULL_PTR_ARG(2);
 			static int SerialStream_RxByte(FILE *Stream) ATTR_NON_NULL_PTR_ARG(1);
 		#endif