tools headers uapi: Grab a copy of fadvise.h

Will be used to generate the string table for fadvise64's 'advice'
argument.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-muswpnft8q9krktv052yrgsc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>