[macOS] remove Growl support, remove unused code
Summary:
Backport Core PR 11268: [macOS] remove Growl support, remove unused code https://github.com/bitcoin/bitcoin/pull/11268 f151f5f50 [macOS] remove Growl support, remove unused code (Jonas Schnelli) Pull request description: There is no longer a reason to support Growl. A) It went to pay-ware since a couple of years B) Since OSX 10.8, the operating system has its own modal notification options (Notification Center). This PR removes support for Growl. OSX notification centre is still supported after this PR.
Test Plan:
make check
confirm Qt GUI runs fine on MacOSX
Reviewers: schancel, #bitcoin_abc
Reviewed By: schancel, #bitcoin_abc
Subscribers: teamcity
Differential Revision: https://reviews.bitcoinabc.org/D1243