perf packaging: add memcpy to perf MANIFEST

There seems to be a new dependency on arch/*/lib/memcpy*.S when compiling
the perf tool.  Make sure that file is included in the MANIFEST when
creating the tarball.

Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1291155133-3499-2-git-send-email-dzickus@redhat.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>