tools headers UAPI: Sync linux/stat.h with the kernel sources

To pick the changes in:

  72d1249e ("uapi: fix statx attribute value overlap for DAX & MOUNT_ROOT")

That don't cause any change in tooling, just addresses this perf build
warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/stat.h' differs from latest version at 'include/uapi/linux/stat.h'
  diff -u tools/include/uapi/linux/stat.h include/uapi/linux/stat.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>