meson: add -pthreads and more libs when -Dlink-udev-shared=false (#6159)
Three binaries would fail to link when ld.bfd was used and link-udev-shared was
false. Add -pthreads (again) to the failing binaries and synchronize the
dependency list between libsystemd-shared .a and .so versions.
Apart from allowing the build to succeed, this shouldn't have much effect becuase
systemd-networkd was already using pthreads.