Removal of 31-bit (s390) glibc packages

[Frank Heimes]

Last cycle there was the effort to turn off COMPAT_32BIT_TIME on s390x (but also on other architectures, LP#2038583).
Based on this effort it was agreed to not only turn off 32-bit time but 32-bit (for the mainframe platform, that is technically 31-bit) entirely.

Two major 31-bit “left-overs” for the mainframe platform are the 31-bit glibc packages (libc6-s390, libc6-dev-s390).

This should be cleaned-up and these should now be removed (and their build disabled) to reach a clean 64-bit s390x system.

But the reverse dependency situation is like follows:

$ reverse-depends --list libc6-s390 -r oracular -a s390x
gcc-snapshot
lib32asan5
lib32asan6
lib32asan8
lib32atomic1
lib32gcc-s1
lib32gfortran5
lib32go14
lib32go16
lib32go19
lib32go21
lib32go22
lib32go23
lib32gomp1
lib32gphobos1
lib32gphobos2
lib32gphobos3
lib32gphobos4
lib32gphobos5
lib32gphobos76
lib32itm1
lib32objc4
lib32stdc++6
lib32stdc++6-10-dbg
lib32stdc++6-11-dbg
lib32stdc++6-12-dbg
lib32stdc++6-13-dbg
lib32stdc++6-14-dbg
lib32stdc++6-9-dbg
lib32ubsan1
lib32z1
libc6-dev-s390
oaklisp

$ reverse-depends libc6-s390 -r oracular -a s390x
Reverse-Depends
===============
* gcc-snapshot
* lib32asan5
* lib32asan6
* lib32asan8
* lib32atomic1
* lib32gcc-s1
* lib32gfortran5
* lib32go14
* lib32go16
* lib32go19
* lib32go21
* lib32go22
* lib32go23
* lib32gomp1
* lib32gphobos1
* lib32gphobos2
* lib32gphobos3
* lib32gphobos4
* lib32gphobos5
* lib32gphobos76
* lib32itm1
* lib32objc4
* lib32stdc++6
* lib32stdc++6-10-dbg
* lib32stdc++6-11-dbg
* lib32stdc++6-12-dbg
* lib32stdc++6-13-dbg
* lib32stdc++6-14-dbg
* lib32stdc++6-9-dbg
* lib32ubsan1
* lib32z1
* libc6-dev-s390
* oaklisp

But since kernel dropped support for 31-bit (32-bit) executables, starting with Ubuntu kernel 6.8 (LP#2038583, esp. comment #7 and #11) these libraries should be removed, too.