Fixed compile error when FIXED_CONTROL_ENDPOINT_SIZE compile time option was disabled, and a USE_*_DESCRIPTORS compile time option was not enabled on the AVR8s.

Add C++ compatibility to some header files currently missing extern "C" linkage.

LUFA/Drivers/USB/Core/PipeStream.h

@@ -88,6 +88,11 @@
 		#elif (ARCH == ARCH_UC3)
 			#include "UC3/PipeStream_UC3.h"
 		#endif
+
+	/* Disable C linkage for C++ Compilers: */
+		#if defined(__cplusplus)
+			}
+		#endif
 	
 #endif