build: don't call prereq for any package/symlinks rules

build: don't call prereq for any package/symlinks rules

Most of the time, we want to make sure OpenWrt has been configured and
setup before start running make. However, in case of package/symlinks,
forcing prereq as a dependency creates multiple issues:
*when executed on a clean workspace, it will prompt for user input
 and open a menuconfig window before executing the feeds command
*the only way around that is to provide a .config. However, the "prereq"
 target would then run a "make defconfig", which will remove all the
 packages in the .config but from external feeds, as feeds have not been
 installed yet.

The only way to currently work around this, is to generate a fake config
by running "make defconfig", then "make package/symlinks", copy the real
config (which at this point disregards the previously generated config),
and run make defconfig again. Something like this:

make defconfig
make package/symlinks
cp real.config .config
make defconfig

This change is removing the need for the first defconfig, making the
process more logical for OpenWrt users using the package/symlinks target.

Signed-off-by: Mathieu Olivari <mathieu@qca.qualcomm.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45657 3c298f89-4303-0410-b956-a3cf2f4a3e73