[meson|scripts] update scripts#12945

Merged

strega-nil merged 12 commits intomicrosoft:masterfrom

Neumann-A:make_meson_sane

Nov 18, 2020

Commits on Nov 16, 2020

fix _FLAGS variables
Neumann-A
committed

Commits on Nov 17, 2020

set env SDKROOT and MACOSX_DEPLOYMENT_TARGET in configure_meson
Neumann-A
committed