lib: Add Atmel SAM3x8e ARM CMSIS files

Add the ARM CMSIS definitions (obtained from an Arduino copy of
libsam) in preparation for Arduino Due support.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

lib/cmsis-sam3x8e/cmsis-sam3x8e.patch

@@ -0,0 +1,11 @@
+--- source/gcc/startup_sam3xa.c.orig	2016-06-14 14:20:43.166209461 -0400
++++ source/gcc/startup_sam3xa.c	2016-06-14 14:00:57.497137169 -0400
+@@ -129,7 +129,7 @@
+ void CAN1_Handler       ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
+ 
+ /* Exception Table */
+-__attribute__ ((section(".vectors")))
++__attribute__ ((section(".vectors"))) __attribute__((externally_visible))
+ const DeviceVectors exception_table = {
+ 
+ 	/* Configure Initial Stack Pointer, using linker-generated symbols */