Announcement: https://sourceware.org/pipermail/libc-alpha/2022-August/141193.html
Announcement: https://sourceware.org/pipermail/libc-alpha/2023-February/145190.html

Failing Hydra build: https://hydra.nixos.org/build/189053872

Previously, builds such as `cmake` would fail with errors like this:

    In file included from /nix/store/injyphmxqgi028skp28fsmdvbdb57nvl-glibc-2.36-48-dev/include/linux/fs.h:19,
                     from /build/cmake-3.24.2/Utilities/cmlibarchive/libarchive/archive_read_disk_posix.c:56:
    /nix/store/injyphmxqgi028skp28fsmdvbdb57nvl-glibc-2.36-48-dev/include/linux/mount.h:95:6: error: redeclaration of 'enum fsconfig_command'
       95 | enum fsconfig_command {
          |      ^~~~~~~~~~~~~~~~

The reason behind that is that the kernel exports `linux/mount.h` via
kernel headers APIs that are also defined in `sys/mount.h` from glibc.
To avoid clashes, safeguards were implemented in glibc to prevent this
from happening[1][2].

However, these `#ifndef`-safeguards are removed by `fixincludes` during
gcc's build and the (broken) result is subsequently copied into
`include-fixed/sys/mount.h` which is added to each build via the
cc-wrapper. To work around this, I decided to simply drop the file: it
also exists in glibc's output and our gcc12 doesn't seem to expose this
anymore anyways.

[1] Commit bb1e8b0ca99b5cbedfae3e6245528a87d95ff3e2
[2] Commit 3bd3c612e98a53ce60ed972f5cd2b90628b3cba5

Failing Hydra build: https://hydra.nixos.org/build/193327405
Same fix as for gcc11.

Failing Hydra build: https://hydra.nixos.org/build/193342322
Patch from gcc11 requires some minor adjustments to properly apply.

Failing Hydra build: https://hydra.nixos.org/build/193370420

Failing Hydra build: https://hydra.nixos.org/build/193340626

Failing Hydra build: https://hydra.nixos.org/build/193371579

Failing Hydra build: https://hydra.nixos.org/build/193330218

Failing Hydra build: https://hydra.nixos.org/build/193374680

Failing Hydra build: https://hydra.nixos.org/build/193338640

We don't need the `meson.build` fixes because (1) lxc4 doesn't use meson
and (2) it contains some fixes to make sure it works both with newer and
older glibc versions. Since we only ship glibc 2.36 from now on, we can
skip that.

Failing Hydra build: https://hydra.nixos.org/build/193347368

Failing Hydra build: https://hydra.nixos.org/build/193339001

Failing Hydra build: https://hydra.nixos.org/build/193332774

The functions pidfd_open & pidfd_send_signal are now part of `glibc`,
but defined in the header `sys/pidfd.h` which is not included in
`bindings.c`.

Failing Hydra build: https://hydra.nixos.org/build/193376808

Failing Hydra build: https://hydra.nixos.org/build/193323749

Failing Hydra build: https://hydra.nixos.org/build/193810432

To correctly find the implementation of `pidfd_open` - which was
introduced in glibc 2.36 - an additional `#include` is needed. The newly
introduced patch adds that.

Failing Hydra build: https://hydra.nixos.org/build/214432977

Failing Hydra build: https://hydra.nixos.org/build/214419156
Relevant upstream thread: https://lore.kernel.org/qemu-devel/20230110174901.2580297-1-berrange@redhat.com/