Glibc 2.34 dropped support for __morecore hooks needed to implement
the hugepage-backed malloc in libhugetlbfs. As a result, libhugetlbfs
FTBFS. Based on discussions in upstream (libhugetlbfs) bug tracker[0],
bringing back the functionality in libhugetlbfs is going to require
significant effort (developing an alternate allocator).

An alternate solution is to use glibc 2.35, where support has been
added for a tunable ('GLIBC_TUNABLES=glibc.malloc.hugetlb=2') to
enable hugepage backed allocation.

In the meanwhile, apply a patch[1] to detect the absence of __morecore
and disable dependent functionality. Although not ideal, it allows the
rest of the features provided by libhugetlbfs to continue to be
available.

Closes: #1017324
[0] https://github.com/libhugetlbfs/libhugetlbfs/issues/52
[1] https://github.com/libhugetlbfs/libhugetlbfs/pull/63

Upstream recently gained support for the RISC-V architecture. There's
ongoing effort to enable the port in debian.

Enable the architecture in the package to allow wider testing of
upstream but also kernel support for TLB hugepages.

Upstream version 2.23

Upstream has transitioned to using python3. Let's update our build
dependencies to reflect this change.

Closes: #936874

Upstream has dropped manpage for non-existent binary. Let's update our
patchstack to drop the patch doing this.

Update to upstream version '2.22'
with Debian dir e8a358280a0761b57f37b7721cefd7d76faacae7

The version used for Breaks+Replaces was incorrectly set to 2.21-3
instead of 2.21-2. Correct this.

ld.hugetlbfs moved from libhugetlbfs0 to libhugetlbfs-bin in 2.21-2
but didn't specify Breaks+Replaces. This broke upgrade of the package
in testing. Fix this.

libhugetlbfs includes a script and linker files to allow automatically
linking against libhugetlbfs. Shipping these files as part of the
library package causes conflict multiarch conflicts. Let's move it to
the binary package as that's where the tools related to libhugetlbfs
live.

ld.hugetlbfs was being installed to /usr/share as opposed to
/usr/bin where it is normally expected. This generates a warning from
the multi-arch hinter. Fix this by moving the file to /usr/bin.

The debian package is carrying patches that were cherry-picked from
upstream. Some of these are now available as part of new upstream
release - drop them from the debian package patch queue.

Update to upstream version '2.21'
with Debian dir f9bef759b12293ea9c5040d6eecaf986ec2adead

Upstream doesn't support all the architectures supported by Debian. In
some instances (e.g., mips) the kernel has support for hugetlbfs but
it is missing from libhugetlbfs.

Restrict the architectures to those supported by upstream.

Closes: #879939.

libhugetlbfs-dev has the same content across architecture. As such
mark it to be "Multi-Arch: same".

dh-exec is not actually required for installing the package. Drop this
dependency.