perf data: Move perf_dir_version into data.h

perf_dir_version belongs to struct perf_data which is declared in data.h.
To allow its use in inline perf_data functions, move perf_dir_version to
data.h

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191004083121.12182-3-adrian.hunter@intel.com


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