imagebuilder: Fix sorting package list breaks opkg dependency handling for provides

imagebuilder: Fix sorting package list breaks opkg dependency handling for provides

When imagebuild sorts package lists it breaks opkg's ability to realize
that a providers for a Provides has already been installed, when the sort
results in the provider being later in the list of packages that a package
which depends on a Provides (and hence the provider is not yet installed
for opkg to realize the provider was available doesn't not handle the case
of a package that is to be installed satisfying a dependency, only one that
is already installed (or which it schedules to be installed, which in the
absence of an installed provider is whichever provider happens to be the
default)

Signed-off-by: Daniel Dickinson <openwrt@daniel.thecshore.com>