Add a PT_NOTE section to mark build_id.

nacl/dyn-link/ldscripts/elf64_nacl.x

Index: nacl/dyn-link/ldscripts/elf64_nacl.x
diff --git a/nacl/dyn-link/ldscripts/elf64_nacl.x b/nacl/dyn-link/ldscripts/elf64_nacl.x
index 927cf874907b3a665caf04bb482dc7a3f2b349c8..bf077dc125c1a08ad009a60f2714cd8fde5cf9f1 100644
--- a/nacl/dyn-link/ldscripts/elf64_nacl.x
+++ b/nacl/dyn-link/ldscripts/elf64_nacl.x
@@ -14,6 +14,7 @@ PHDRS
   seg_dynamic  PT_DYNAMIC FLAGS(6) ;
   seg_stack    PT_GNU_STACK FLAGS(6) ;
   seg_tls      PT_TLS FLAGS(4) ;
+  seg_build_id PT_NOTE FLAGS(4) ;

[Mark Seaborn, 2013/08/02 00:31:11]

Make this "seg_note".  It can potentially contain other notes.  Same for the
other files too.

 }
 SECTIONS
 {
@@ -52,8 +53,8 @@ SECTIONS
     PROVIDE_HIDDEN (__note_gnu_build_id_start = .);
     *(.note.gnu.build-id)
     PROVIDE_HIDDEN (__note_gnu_build_id_end = .);
-  } :seg_rodata
-  .hash           : { *(.hash) }
+  } :seg_rodata :seg_build_id
+  .hash           : { *(.hash) } :seg_rodata
   .gnu.hash       : { *(.gnu.hash) }
   .dynsym         : { *(.dynsym) }
   .dynstr         : { *(.dynstr) }