Backport fixes for tests on kernels >= 5.1

In Debian, glibc 2.8 is shipped in Buster with the 4.19 kernel, while
Bullseye ships newer versions of both.

In Apertis we also ship the Buster base with newer kernels, 5.4 in v2020
and 5.8 in v2021. This means that we can hit issues that do not manifest
in Debian since those are combinations that do not get tested there.

This is one of those cases, where some changes in the kernel headers
broke the glibc testsuite. Upstream ships the fixes in the 2.9 branch,
so here we backport a few patches to make the tests happy again.

In particular, with the 5.4 and 5.7 kernels we hit these failures:

    FAIL: conform/POSIX2008/arpa/inet.h/conform
    FAIL: conform/POSIX2008/netdb.h/conform
    FAIL: conform/POSIX2008/netinet/in.h/conform
    FAIL: conform/POSIX2008/sys/socket.h/conform
    FAIL: conform/UNIX98/arpa/inet.h/conform
    FAIL: conform/UNIX98/netdb.h/conform
    FAIL: conform/UNIX98/netinet/in.h/conform
    FAIL: conform/UNIX98/sys/socket.h/conform
    FAIL: conform/XOPEN2K/arpa/inet.h/conform
    FAIL: conform/XOPEN2K/netdb.h/conform
    FAIL: conform/XOPEN2K/netinet/in.h/conform
    FAIL: conform/XOPEN2K/sys/socket.h/conform
    FAIL: conform/XOPEN2K8/arpa/inet.h/conform
    FAIL: conform/XOPEN2K8/netdb.h/conform
    FAIL: conform/XOPEN2K8/netinet/in.h/conform
    FAIL: conform/XOPEN2K8/sys/socket.h/conform
    FAIL: conform/XPG42/arpa/inet.h/conform
    FAIL: conform/XPG42/netdb.h/conform
    FAIL: conform/XPG42/netinet/in.h/conform
    FAIL: conform/XPG42/sys/socket.h/conform
    FAIL: io/tst-copy_file_range
    FAIL: misc/check-installed-headers-c

The backported patch address the issues below:

* https://sourceware.org/bugzilla/show_bug.cgi?id=24532
* https://bugzilla.redhat.com/show_bug.cgi?id=1769304



Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>