This adds the `validatePkgConfig` hook, which can be used to validate
pkg-config files in the output(s). Currently, this will just run
`pkg-config --validate` on all `.pc` files, capturing errors such as
the issue that was fixed in #87789.

The hook could be extended in the future with more fine-grained
checks.

ed16f83 made all dependencies explicit, including systemd, which makes the
build step to fail on macOS. Here systemd is added to runtimePath only if the
target system is Linux

hugo: 0.71.1 -> 0.72.0

yabai: 3.0.1 -> 3.0.2

hyperfine: install man and shell completion

redshift: enable appindicator support

vsftpd: listen on both address families

appimage: replace radare2+jq with readelf+awk+sha256sum

colormake: use fetchFromGitHub

go-bindata: use fetchFromGitHub

unit: Expose PHP expressions used so it can easily be accessed for configs

docker-compose: fix zsh completion

keybase-gui: set platforms to x86_64-linux

gnuradio: 3.7.13.4 -> 3.7.14.0

libversion: Fix unsafe concatenation of $LD_LIBRARY_PATH

uclibc: 1.0.33 -> 1.0.34

matrix-synapse: 1.13.0 -> 1.14.0

https://github.com/go-gitea/gitea/releases/tag/v1.11.6

Naive concatenation of $LD_LIBRARY_PATH can result in an empty
colon-delimited segment; this tells glibc to load libraries from the
current directory, which is definitely wrong, and may be a security
vulnerability if the current directory is untrusted.  This particular
case probably has no security relevance, but we should avoid this
unsafe pattern anyway in case it gets copied.  See #76804.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

mlv-app: init at 1.11

formally -> formerly

gitlab: 12.8.10 -> 12.10.6

cocoapods: 1.9.2 -> 1.9.3

jc: 1.10.12 -> 1.11.1

act: 0.2.8 -> 0.2.9

sbcl: add option to disable immobile space

Programs which generate and compile a lot of code at runtime (such as
programming language interpreters like ACL2) are not suited for running on SBCL
executables built with the "immobile space" feature, as explained by Douglas
Katzman in this mail thread:

  https://sourceforge.net/p/sbcl/mailman/message/36007057/

In this commit, I add an optional flag to the SBCL package allowing you to
disable the "immobile space" features.

I also migrated away from specifying enabled/disabled features in a
`customize-target-features.lisp` file and towards supplying them as command line
arguments to `make.sh`, as has been recommended by the installation instructions
since 2012 or so.