nss-myhostname: skip it when systemd

nss-myhostname: skip it when systemd

Fixed error when systemd is in DISTRO_FEATURES:
ERROR: The recipe systemd is trying to install files into a sharedarea when those files already exist. Those files and their manifestlocation are:
   /path/to/sysroots/qemux86/usr/lib/libnss_myhostname.so.2
 Matched in manifest-qemux86-nss-myhostname.populate_sysroot
Please verify which recipe should provide theabove files.

(From OE-Core rev: da70a62d456f7efac379381c2c431cc4ded877e9)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>