Add build tests to verify correct compilation of as many modules as possible under as many architectures as possible.

Fix broken compilation of LUFA under C++ compilers when the Serial peripheral module header file is included in a C++ source file.

Fix missing semicolon in the UC3 architecture host pipe functions.

Fix failed compilation for the XMEGA architecture if USB_DEVICE_ONLY us not specified.

LUFA/Drivers/USB/Core/UC3/Pipe_UC3.c

@@ -80,7 +80,7 @@ bool Pipe_ConfigurePipe(const uint8_t Number,
 		}
 		else
 		{
-			UPCFG0Temp = (&AVR32_USBB.upcfg0)[PNum]
+			UPCFG0Temp = (&AVR32_USBB.upcfg0)[PNum];
 		}
 
 		if (!(UPCFG0Temp & AVR32_USBB_ALLOC_MASK))