Dunno if this is a problem with me using an older Ubuntu or not, but the issue is lack of meson. Apparently the python 3.6 on this ubuntu install also lacks pip, so I had to get that too, and then:
python3 -m pip install meson
to get the build to continue. Should also note that installing meson through apt doesn't work because it's an outdated version with a major bug (apt gets you 0.45, pip gets you something in the 0.5x range).
Dunno if this is a problem with me using an older Ubuntu or not, but the issue is lack of meson. Apparently the python 3.6 on this ubuntu install also lacks pip, so I had to get that too, and then:
python3 -m pip install meson
to get the build to continue. Should also note that installing meson through apt doesn't work because it's an outdated version with a major bug (apt gets you 0.45, pip gets you something in the 0.5x range).