Add a PT_NOTE section to mark build_id.

nacl/dyn-link/ldscripts/elf_nacl.x

Index: nacl/dyn-link/ldscripts/elf_nacl.x
diff --git a/nacl/dyn-link/ldscripts/elf_nacl.x b/nacl/dyn-link/ldscripts/elf_nacl.x
index 88042daca97aa028387b9acd79d71cafe0616fa3..3fabd71fe582faec62e9aa632550c46d26a910e5 100644
--- a/nacl/dyn-link/ldscripts/elf_nacl.x
+++ b/nacl/dyn-link/ldscripts/elf_nacl.x
@@ -15,6 +15,7 @@ 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
 {
@@ -53,7 +54,8 @@ 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) }