at-spi2-core now needs libsystemd on Linux

Hi!

I am in my usual pkgrrxx and am getting this build failure in 
devel/at-spi2-core:

[...]

Configuring at-spi-dbus-bus.desktop using configuration
Configuring org.a11y.Bus.service using configuration
Configuring at-spi-dbus-bus.service using configuration
Program dbus-daemon found: YES (/usr/pkg/bin/dbus-daemon)
Program dbus-broker-launch found: YES (/usr/bin/dbus-broker-launch)
Run-time dependency libsystemd found: NO  (tried pkg-config)

bus/meson.build:92:18: ERROR: Dependency "libsystemd" not found (tried 
pkg-config)

The log doesn't say more. As I understand the bus/meson.build file, this 
depends on libsystemd on Linux specifically. And because the pkg-config 
search path does not include /usr/lib64/pkgconfig, libsystemd.pc is not 
found.

What is the correct way to solve this?

  - try to make it not use libsystemd?
  - add /usr/lib64/pkgconfig to the pkg-config search path?
  - add some kind of builtin.mk for libsystemd?
  - add a systemd package?

-- 
Benny