Previously, one had to have a recipe.sh in all recipe directories in
order to run `make clean` successfully. This fixes that.

Signed-off-by: Wren Turkal <wt@penguintechs.org>

`make` is `gmake` on FreeBSD, so add a variable to include this change in command.

by adding the CARGO_PACKAGE variable, which passes --package=PKG to
cargo rustc.

A hardcoded strip does not work when cross compiling.