https://hydra.nixos.org/build/274565015/nixlog/1
`pcre` is no longer needed as the comment longer applies.
`glib-2.0.pc` now has `libsysprof-capture-4` in `Requires.private` field.
Normally, this does not matter since we patch our `pkg-config` to ignore that
outside of static builds but `entangle` was using `pkgconf`, which is not patched.
Let’s switch to standard `pkg-config`.
This will also allow us to clean some more dependencies.
Unfortunately, this also reveals issue with an underspecified `gio-unix-2.0` dependency so we need to fix that.