mlog: make mlog helper take once keyword argument
mlog: make mlog helper take once keyword argument

We really want to have this in the log method as well.

Fixes: #8002

pexip/meson,jpakkane/meson,mesonbuild/meson,pexip/meson,pexip/meson,QuLogic/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,jpakkane/meson,QuLogic/meson,pexip/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,QuLogic/meson,jpakkane/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,jpakkane/meson,jpakkane/meson,mesonbuild/meson,jpakkane/meson,mesonbuild/meson,mesonbuild/meson,QuLogic/meson,mesonbuild/meson,QuLogic/meson,pexip/meson,QuLogic/meson,pexip/meson