Fix nacl-gdb so that it can read ELF core dump files

gdb/amd64-linux-tdep.c

Index: gdb/amd64-linux-tdep.c
diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index d9192164ec41ed89a611b6a097b0422eff3e07c9..e3683eda21ae5421a272c2fe76c3f357ef435ff8 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -1526,6 +1526,14 @@ amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch)
   tdep->i386_syscall_record = amd64_linux_syscall_record;
 }
 
+void
+amd64_linux_init_gregset (struct gdbarch_tdep *tdep)
+{
+  tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
+  tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
+  tdep->sizeof_gregset = 27 * 8;
+}
+
 static void
 amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -1537,10 +1545,7 @@ amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 
   gdb_assert (tdesc_data);
 
-  tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
-  tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
-  tdep->sizeof_gregset = 27 * 8;
-
+  amd64_linux_init_gregset (tdep);
   amd64_init_abi (info, gdbarch);
 
   /* Reserve a number for orig_rax.  */