Adding __ram_end__ in linker scripts

variants/arduino_zero/linker_scripts/gcc/flash.ld

@@ -182,10 +182,12 @@ SECTIONS
 
 	/* Set stack top to end of RAM, and stack limit move down by
 	 * size of stack_dummy section */
-	__StackTop = ORIGIN(RAM) + LENGTH(RAM);
+	__StackTop = ORIGIN(RAM) + LENGTH(RAM) ;
 	__StackLimit = __StackTop - SIZEOF(.stack_dummy);
 	PROVIDE(__stack = __StackTop);
 
+	__ram_end__ = ORIGIN(RAM) + LENGTH(RAM) -1 ;
+
 	/* Check if data + heap + stack exceeds RAM limit */
 	ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed with stack")
 }

variants/arduino_zero/linker_scripts/gcc/flash_with_bootloader.ld

@@ -186,6 +186,8 @@ SECTIONS
 	__StackLimit = __StackTop - SIZEOF(.stack_dummy);
 	PROVIDE(__stack = __StackTop);
 
+	__ram_end__ = ORIGIN(RAM) + LENGTH(RAM) -1 ;
+
 	/* Check if data + heap + stack exceeds RAM limit */
 	ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed with stack")
 }