Specify the Cargo.toml location
Cargo is usually pretty good at finding the
Cargo.toml for building the top-level project, but when trying to build the project from outside the repo (
ninja -C fractal/_build) it doesn't work.
It is especially problematic when trying to create a
dist archive (
ninja dist), meson clones the project in a temporary directory and builds it without changing the current working directory.
Before this MR,
ninja dist should fail, after it it should work.