lib: Modify SAM3X CMSIS files to work with GCC's lto feature

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

lib/README

@@ -20,7 +20,8 @@ with gcc's LTO feature. See cmsis-sam3x8e.patch for the modifications.
 The sam3x directory contains code from the
 Atmel.SAM3X_DFP.1.0.50.atpack zip file found at:
   http://packs.download.atmel.com/
-version 1.0.50 (extracted on 20180725).
+version 1.0.50 (extracted on 20180725). It has been modified to
+compile with gcc's LTO feature. See sam3x.patch for the modifications.
 
 The lpc176x directory contains code from the mbed project:
   https://github.com/ARMmbed/mbed-os

lib/sam3x/gcc/gcc/startup_sam3xa.c

@@ -132,7 +132,7 @@ void CAN0_Handler   ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
 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 */

lib/sam3x/sam3x.patch

@@ -0,0 +1,13 @@
+diff --git a/lib/sam3x/gcc/gcc/startup_sam3xa.c b/lib/sam3x/gcc/gcc/startup_sam3xa.c
+index 337a6d3c..dcf56447 100644
+--- a/lib/sam3x/gcc/gcc/startup_sam3xa.c
++++ b/lib/sam3x/gcc/gcc/startup_sam3xa.c
+@@ -132,7 +132,7 @@ void CAN0_Handler   ( void ) __attribute__ ((weak, alias("Dummy_Handler")));
+ 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 */