Fix small Mac OSX memory leak (imported from BU sources)
Summary:
I noticed there was a very small memory leak in the way CoreFoundation objects were being used on Mac OSX. I submitted that patch months ago to the BU team to fix it, and it's been accepted and merged into their repository. I wanted to bring that patch here to our project, just as a small nit, because it bugs me the way Core originally wrote this code. They clearly don't know how to use the CoreFoundation API ;)
Here is the reference in the BU repository:
Test Plan: Compile on OSX if you dare, open Qt gui app, toggle load on startup on/off
Reviewers: deadalnix, sickpig, freetrader, #bitcoin_abc
Reviewed By: freetrader, #bitcoin_abc
Subscribers: ealmansi
Differential Revision: https://reviews.bitcoinabc.org/D452