sdrangel: builds fail for macOS 10.11 and earlier; fix, or set known_fail

[mascguy (Christopher Nielsen)]

It looks like this port is failing to build for macOS releases prior to 10.12. Let's either fix, or set known_fail to eliminate wasted buildbot time.

​https://ports.macports.org/port/SDRangel/details/

[ra1nb0w]

The error is

/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_science_SDRangel/SDRangel/work/sdrangel-6.17.2/plugins/channelrx/radioastronomy/radioastronomy.cpp:363:47: error: no member named 'callOnTimeout' in 'QTimer'
        m_sweepTimerConnection = m_sweepTimer.callOnTimeout(this, f);

probably because the Qt version used by <10.12 doesn't support callOnTimeout() (introduced by Qt 5.12).

I disable SDRangel for macOS < 10.12

[Davide Gerhard <ra1nb0w@…>]

In 6d626f5853f969ef3fbf0e526a4313295da6881d/macports-ports (master):

SDRangel: know_fail for macOS < 10.12 and remove sdrplay

remove sdrplay since it is not available for arm64. No revision bump
since a new version will be available in the next weeks.

Closes: #63771