perf tools: Fix version when building out of tree

perf tools: Fix version when building out of tree

When building perf out of tree:

  $ make perf-tar-src-pkg
  $ tar -xf perf-<ver>.tar -C /tmp
  $ cd /tmp/perf<ver>
  $ make -C tools/perf

you get this warning message:
    make[1]: *** No rule to make target `kernelversion'.  Stop.

Fix it by saving the perf version in the tar file and using that for the
out of tree builds.

v2: removed short form request and fixed up version string from usual output.

Signed-off-by: David Ahern <dsahern@gmail.com>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1383753335-25782-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>