pkg/56707: gnuradio-core build broken on netbsd-9

[nia%pkgsrc.org@localhost]

>Number:         56707
>Category:       pkg
>Synopsis:       gnuradio-core build broken on netbsd-9
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 13 10:35:00 +0000 2022
>Originator:     nia
>Release:        pkgsrc current, netbsd-9
>Organization:
The NetBSD Foundation
>Environment:
>Description:
gnuradio-core has started to require std::filesystem.

This is unavailable with the GCC 7 system compiler used in
NetBSD 9.

This isn't a problem with the way we're building boost - std::filesystem
is a dependency that has been introduced upstream in GNU Radio.

NetBSD's gcc7 is unusual because it doesn't ship with "experimental"
headers that are usually included with GCC. Thus this problem is unique
to NetBSD.
>How-To-Repeat:
Attempt to build gnuradio-core, observe errors:


In file included from /usr/pkg/include/boost/dll/runtime_symbol_info.hpp:11:0,
                 from /tmp/ham/gnuradio-core/work/gnuradio-3.10.0.0/build/gnuradio-runtime/lib/constants.cc:16:
/usr/pkg/include/boost/dll/config.hpp:47:22: error: 'filesystem' is not a namespace-name
 using namespace std::filesystem;
                      ^~~~~~~~~~
>Fix:
Downgrade gnuradio-core, or force pkgsrc gcc and break ARM support.