packagegroup-core-boot: conditionally rdepend on VIRTUAL-RUNTIME_initscripts

packagegroup-core-boot: conditionally rdepend on VIRTUAL-RUNTIME_initscripts

If we are building a systemd image with 'sysvinit' not in DISTRO_FEATURES,
the initscripts should not be installed into the image, as they are useless.
What's more, we as now support executing scripts under /etc/rcS.d, the
boot time will be increased by these scripts as the systemd will try to
translate them into temporary service files.

These init scritps are actually needed only when 'sysvinit' is in
DISTRO_FEATURES.

(From OE-Core rev: 74b931909e58fc581bb52c1af1f3ae26602980f3)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>