Weird build-gnuradio failures on Ubuntu

Got around to looking at build failures on Ubuntu today (on versions
where it previously worked).

It turns out that Ubuntu renamed the libzmq packages to libzmq1 and
the --ignore-missing directive isn’t really what you expect it to be–it
ignores repo failures, NOT “I’ve never heard of this package
before”. This combination of these two things is, IMHO, horrific. But I
have a say, so I updated build-gnuradio to use the new package names
for libzmq. A distribution retroactively changing package names is
totally wrong, in my opinion. But again, I don’t really have a