[FS#364] Please add debug package ala debian way

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - bastien-roucaries (bastien-roucaries) 

Attached to Project - LEDE Project
Summary - Please add debug package ala debian way
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Critical
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Debian add debug package 

it save space by stripping debug symbols but allow debugging easily by loading debug package

implementation is described here
https://wiki.debian.org/AutomaticDebugPackages

This could be implemented by finding all ELF files and call objcopy --only-keep-debug on them, and put the symbols into /usr/lib/debug/original path into the -dbgsym package. dh_strip has a similar feature, but has a different semantics in different compatibility levels, and generally interacts too much with the packaging to use it in a robust and generic way. 

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=364