Include samd.h instead of sam.h

The sam.h file uses some non-portable macros that raise a warning in
newer gcc version. This warning was supressed in commit 8575a52 (Add
-Wno-expansion-to-defined compile warning flag), but this is not ideal.

However, since the only thing sam.h does is figure out what CPU is
selected and include the right family header, and we always use SAMD21
CPUs, the only thing sam.h does is include samd.h.

So we can easily bypass then and include samd.h directly.

This fixes the first part of #556.

Author: matthijskooijman

cores/arduino/Arduino.h

@@ -45,7 +45,7 @@ extern "C"{
 #endif // __cplusplus
 
 // Include Atmel headers
-#include "sam.h"
+#include <samd.h>
 
 #include "wiring_constants.h"
 

cores/arduino/SERCOM.h

@@ -19,7 +19,7 @@
 #ifndef _SERCOM_CLASS_
 #define _SERCOM_CLASS_
 
-#include "sam.h"
+#include <samd.h>
 
 #define SERCOM_FREQ_REF      48000000
 #define SERCOM_NVIC_PRIORITY ((1<<__NVIC_PRIO_BITS) - 1)

cores/arduino/WVariant.h

@@ -19,7 +19,7 @@
 #pragma once
 
 #include <stdint.h>
-#include "sam.h"
+#include <samd.h>
 
 #ifdef __cplusplus
 extern "C" {

cores/arduino/cortex_handlers.c

@@ -16,7 +16,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
-#include <sam.h>
+#include <samd.h>
 #include <variant.h>
 #include <stdio.h>
 

cores/arduino/startup.c

@@ -16,7 +16,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
-#include "sam.h"
+#include <samd.h>
 #include "variant.h"
 
 #include <stdio.h>

cores/arduino/wiring_private.h

@@ -27,7 +27,7 @@ extern "C" {
 #endif
 
 // Includes Atmel CMSIS
-#include "sam.h"
+#include <samd.h>
 
 #include "wiring_constants.h"