[Qt, OSX] QProgressBar CPU-Issue workaround
[Qt, OSX] QProgressBar CPU-Issue workaround

fixes #5295

(cherry picked from commit 6093aa1bb03b03331cc2f48d8f6b749f8817c016)

reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin