Continue to allow building with older meson
Continue to allow building with older meson

Commit 83d46b05792 bumped the minimum meson version to 0.46.0
This makes building on current Ubuntu LTS release more difficult
as it contains 0.45.0.

Instead conditionalize the build to run that code when on newer
meson.

This commit can be reverted when it's appropriate to bump meson
build dependency.

hughsie/fwupd,hughsie/fwupd,vathpela/fwupd,fwupd/fwupd,fwupd/fwupd,hughsie/fwupd,vathpela/fwupd,fwupd/fwupd,vathpela/fwupd,fwupd/fwupd,vathpela/fwupd,hughsie/fwupd