source_root() function is deprecated in Meson version 0.56.0 because it returns the source root of the parent project if called from a subproject. Why would anyone need Mesa as a meson subproject? It would be used as subproject in a project generated by command buffer "decompiler" for Freedreno. Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com> Reviewed-by: Eric Engestrom <eric@igalia.com> Reviewed-by: David Heidelberg <david.heidelberg@collabora.com> Acked-by: Rob Clark <robdclark@chromium.org> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19901>