[FS#132] Add support for multiple dnsmasq instances

[LEDE Bugs]

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

User who did this - Github Issues (github-import) 

Attached to Project - LEDE Project
Summary - Add support for multiple dnsmasq instances
Task Type - Feature Request
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Github issue #301 reported by https://github.com/kbabioch

Currently dnsmasq can only be configured globally. There are situations where this is not good enough, especially if the goal is to isolate networks from each other. Running multiple dnsmasq instances bound only to specific interfaces solves this issue. This was already requested in the old OpenWRT bug tracker (see here), and patches were developed. Maybe this can finally be included into the mainline source, so people can take advantage of this.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=132