Fix Qt deprectation warning on MacOS
Summary:
Fix this warning on OSX:
../src/qt/guiutil.cpp:984:46: warning: 'width' is deprecated: Use
QFontMetrics::horizontalAdvance [-Wdeprecated-declarations]
const int margin = dialog->fontMetrics().width("X");Test Plan:
On OSX:
ninja all check-bitcoin-qt ./src/qt/BitcoinABC-Qt.app/Contents/MacOS/BitcoinABC-Qt
Check the progress bar looks like before this patch.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Subscribers: deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D7888