flash.ld: fix mis-aligned .data section

The end of the .data section in flash must be explicitly word-aligned,
otherwise corruption can occur in a .data section that happens to contain
non-word aligned data.

Author: eriknyquist

variants/arduino_101/linker_scripts/flash.ld

@@ -113,6 +113,7 @@ SECTIONS
 	__data_ram_start = .;
 	*(.data)
 	*(".data.*")
+	. = ALIGN(4);
 	} > SRAM
 
     __data_ram_end = .;