Add a PT_NOTE section to mark build_id.

nacl/dyn-link/ldscripts/elf64_nacl.xs

Index: nacl/dyn-link/ldscripts/elf64_nacl.xs
diff --git a/nacl/dyn-link/ldscripts/elf64_nacl.xs b/nacl/dyn-link/ldscripts/elf64_nacl.xs
index 68f093618981d4d3e05873d32c83c70c48e7dccc..9ef0bf532e96db773734d20b82b92430ff38784f 100644
--- a/nacl/dyn-link/ldscripts/elf64_nacl.xs
+++ b/nacl/dyn-link/ldscripts/elf64_nacl.xs
@@ -13,6 +13,7 @@ PHDRS
   seg_dynamic  PT_DYNAMIC FLAGS(6) ;
   seg_stack    PT_GNU_STACK FLAGS(6) ;
   seg_tls      PT_TLS FLAGS(4) ;
+  seg_note     PT_NOTE FLAGS(4) ;
 }
 SECTIONS
 {
@@ -52,7 +53,8 @@ SECTIONS
     PROVIDE_HIDDEN (__note_gnu_build_id_start = .);
     *(.note.gnu.build-id)
     PROVIDE_HIDDEN (__note_gnu_build_id_end = .);
-  } :seg_rodata
+  } :seg_rodata :seg_note
+  .dummy : {} : seg_rodata
   .hash           : { *(.hash) }
   .gnu.hash       : { *(.gnu.hash) }
   .dynsym         : { *(.dynsym) }