Fixes the `kwargs` handling.
Fixes the `kwargs` handling.

As suggested by @jeandet.

Details:
https://github.com/mesonbuild/meson/pull/2529#pullrequestreview-72703268

jpakkane/meson,jpakkane/meson,becm/meson,MathieuDuponchelle/meson,MathieuDuponchelle/meson,jeandet/meson,pexip/meson,trhd/meson,pexip/meson,ernestask/meson,trhd/meson,MathieuDuponchelle/meson,ernestask/meson,jpakkane/meson,jpakkane/meson,QuLogic/meson,jpakkane/meson,jpakkane/meson,ernestask/meson,jeandet/meson,jpakkane/meson,trhd/meson,jeandet/meson,jeandet/meson,mesonbuild/meson,becm/meson,mesonbuild/meson,thiblahute/meson,becm/meson,QuLogic/meson,becm/meson,ernestask/meson,thiblahute/meson,MathieuDuponchelle/meson,pexip/meson,jeandet/meson,jeandet/meson,thiblahute/meson,trhd/meson,thiblahute/meson,pexip/meson,QuLogic/meson,thiblahute/meson,QuLogic/meson,jpakkane/meson,becm/meson,mesonbuild/meson,mesonbuild/meson,ernestask/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,mesonbuild/meson,MathieuDuponchelle/meson,ernestask/meson,QuLogic/meson,trhd/meson,mesonbuild/meson,becm/meson,pexip/meson,pexip/meson,jeandet/meson,thiblahute/meson,trhd/meson,thiblahute/meson,trhd/meson,pexip/meson,trhd/meson,mesonbuild/meson,MathieuDuponchelle/meson,trhd/meson,jeandet/meson,ernestask/meson,becm/meson,mesonbuild/meson,QuLogic/meson,mesonbuild/meson,becm/meson,MathieuDuponchelle/meson,jeandet/meson,thiblahute/meson,QuLogic/meson,ernestask/meson,becm/meson,pexip/meson,MathieuDuponchelle/meson,becm/meson,pexip/meson,ernestask/meson,QuLogic/meson,MathieuDuponchelle/meson,thiblahute/meson