The nslookup is not shipped for now, we should disable its man page if
the binary tool is not installed.
[YOCTO#3754]
(From OE-Core rev: 1a31918733a7f8479220c01fc99dd9099fdcaf9b)
Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>