base-files: set kernel.core_pattern in sysctl.conf

Move the pattern setting from netifd's service script to
/etc/sysctl.conf.  Put the timestamp component '%t' just after
executable name '%e' for more natural order from output of ls command.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

SVN-Revision: 46867

package/network/config/netifd/files/etc/init.d/network

@@ -21,7 +21,6 @@ start_service() {
 	procd_set_param watch network.interface
 	[ -e /proc/sys/kernel/core_pattern ] && {
 		procd_set_param limits core="unlimited"
-		echo '/tmp/%e.%p.%s.%t.core' > /proc/sys/kernel/core_pattern
 	}
 	procd_close_instance
 }