Core-updates after the staging merge

[Andreas Enge <andreas@enge.fr>]

Hello all,

the merge of staging to master, and the subsequent merge of master to
core-updates did break a few things; but on the positive side, we are
halfway there with getting rid of the staging and core-updates branches ;-)
CI has almost caught up on x86_64; looking at the dashboard at
   https://ci.guix.gnu.org/eval/402403/dashboard
shows much more red than on master, so we will need to do some more work
before the merge. Since it is ordered alphabetically and our package names
often start by the language, red streaks often indicate problems with
a given programming language. There are things to work on for most of the
teams!

- rust: This one bootstrapped up to the latest version! There are a few
  red dots for individual packages.
- python: It is mostly green, but with lots of red, including at least
  one package that prevents icecat from building. I would call for careful
  updates and bug fixes to move on; leaf packages can be updated to the
  latest version, but for important intermediate packages please be
  careful.
- Go looks good.
- Java is red, but apparently still bootstrapping; everything hinges on
  icedtea@2.6, which is still scheduled for build:
     https://ci.guix.gnu.org/build/1007080/details
  So we need to wait, and potentially restart jobs that are marked as
  failed, but may actually build once their inputs are there.
- Everything common lisp related is red (cl-*, sbcl-*), but maybe there
  is a similar thing going; or maybe not, since clisp is built.
- R is red, but for the time being held up by texlive packages still being
  built.
- ghc is taking a long time...

A single package holds up a lot (gtk+ and so on): openldap. It fails after
about a minute of compiling like so:
  starting phase `provide-libldap_r'
  error: in phase 'provide-libldap_r': uncaught exception:
  unbound-variable #f "Unbound variable: ~S" (ungexp) #f
  phase `provide-libldap_r' failed after 0.0 seconds
This looks more like a typo than anything else.


On i686, we are still stuck by wget.


On aarch64, I think we are mainly stuck by lack of build power. I cancelled
a few build jobs on CI belonging to older git commits, but there is not much
we can do apart from bringing back build machines.

On powerpc, my cancelling of old jobs has apparently also cancelled newer
jobs that are actually the same; I am trying to restart them all, but am
not sure if I succeed. Apologies! As written yesterday, CI does not seem
to use all the build power at our disposal for this architecture.

Andreas