build-sys: meson: use target_machine.cpu_family() for CANONICAL_HOST
requested to merge igor.v.kovalenko/pulseaudio:pr/meson-use-target-machine-cpu-family-canonical-host into master
See https://mesonbuild.com/Reference-manual.html#target_machine-object and list of CPU families https://mesonbuild.com/Reference-tables.html#cpu-families
Should be no change to CANONICAL_HOST value in simple same-host builds.