Fix build failures on non-SAM E boards

Author: jepler

src/CAN.h

@@ -4,7 +4,9 @@
 #ifndef CAN_H
 #define CAN_H
 
-#ifdef ARDUINO_ARCH_ESP32
+#if defined(ADAFRUIT_FEATHER_M4_CAN)
+#include "CANSAME5x.h"
+#elif defined(ARDUINO_ARCH_ESP32)
 #include "ESP32SJA1000.h"
 #else
 #include "MCP2515.h"

src/CANSAME5x.cpp

@@ -1,6 +1,7 @@
 // Copyright 2020 © Jeff Epler for Adafruit Industries. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+#if defined(ADAFRUIT_FEATHER_M4_CAN)
 #include <stdint.h>
 #include <stdlib.h>
 
@@ -501,3 +502,7 @@ void CAN1_Handler() {
 }
 
 CANSAME5x *CANSAME5x::instances[2];
+
+CANSAME5x CAN;
+
+#endif

src/CANSAME5x.h

@@ -50,3 +50,5 @@ class CANSAME5x : public CANControllerClass {
   friend void CAN0_Handler(void);
   friend void CAN1_Handler(void);
 };
+
+extern CANSAME5x CAN;