perf symbols: Define EM_AARCH64 for older OSes

4886f2ca added an arm-64 check, but the EM_AARCH64 macro is not
defined in older releases (e.g., RHEL6). Define if it is not defined.

Signed-off-by: David Ahern <david.ahern@oracle.com>
Cc: Victor Kamensky <victor.kamensky@linaro.org>
Link: http://lkml.kernel.org/r/1424306017-96797-1-git-send-email-david.ahern@oracle.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>