build: Drop Ubuntu 21.10 & 21.04 that are EOL

Ubuntu 21.10 and 21.04 are EOL so drop them.

Except that 21.10 is the latest release that supports Power8, so if
we're running on Power8 then stick with 21.10. This requires a hack in
the Dockerfile to switch the APT sources to old-releases.ubuntu.com.

Author: mpe

build/Makefile

@@ -13,8 +13,7 @@ ifeq ($(shell uname -m),ppc64le)
 endif
 
 FEDORA_DISTROS := fedora@${FEDORA_LATEST} fedora@35 fedora@34 fedora@33 fedora@31 fedora
-# Sort is to elimiate duplicates if UBUNTU_LATEST == 21.10
-UBUNTU_DISTROS := $(sort ubuntu@${UBUNTU_LATEST} ubuntu@21.10 ubuntu@21.04 ubuntu@20.04 ubuntu@18.04 ubuntu@16.04 ubuntu)
+UBUNTU_DISTROS := ubuntu@${UBUNTU_LATEST} ubuntu@20.04 ubuntu@18.04 ubuntu@16.04 ubuntu
 KORG_DISTROS := korg@12.1.0 korg@11.3.0 korg@11.1.0 korg@10.3.0 korg@9.4.0 korg@9.3.0 korg@8.5.0 korg@8.1.0 korg@5.5.0
 ALL_DISTROS := ${UBUNTU_DISTROS} ${KORG_DISTROS} ${FEDORA_DISTROS}
 DOCS_DISTRO := docs@${UBUNTU_LATEST}

build/ubuntu/Dockerfile

@@ -7,6 +7,9 @@ ARG apt_mirror
 ENV apt_mirror=${apt_mirror}
 RUN [ -n "$apt_mirror" ] && sed -i -e "s|ports.ubuntu.com|$apt_mirror|" /etc/apt/sources.list || true
 
+# Deal with Ubuntu 21.10 repos moving to old-releases (ppc64le only)
+RUN [ "$from" = "ubuntu:21.10" ] && sed -i -e "s|ports.ubuntu.com/ubuntu-ports|old-releases.ubuntu.com/ubuntu|" /etc/apt/sources.list || true
+
 RUN apt-get -q -y update && \
     DEBIAN_FRONTEND=noninteractive \
     apt-get -q -y install --no-install-recommends \