Fedora 29 is no longer available, and I need to rebuild these images so
libpcre is pre-downloaded as a subproject.
Update them to Fedora 31, which is what we use in `fedora.Dockerfile`.
This should allow some blobs to be shared in the container repository.
This isn’t the latest Fedora release, but I don’t want to go through the
hassle of updating all the CI images to F33 right now in addition to
updating the subproject caches.
`python-unversioned-command` is needed because the Android NDK calls
`python` without a version number. F29 must have installed this already.
The Android NDK setup appears to be OK with Python 3.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #962
The Fedora image we use contains MinGW bits that ought to go into
their own Docker container. This avoids having a massive Docker image
that gloms everything and is harder to update.
While we're splitting off, we can also update to Fedora 29, as we can
rely on Fedora packagers doing their job and ensuring that the MinGW
cross-compilation toolchain still works.
