When cross-compiling a rust package, all we need is the std library compiled
for the target. This uses the final stage compiler which was built for Build
and then uses that as a stage0 compiler for target std library.
It also copies the rust binary from pkgsBuildBuild so that it find the new
lib/rustlib directory.
We also need to create a cargo wrapper which will use the "new" rust compiler
Also makes sure man pages and doc pages are propagated
Co-authored-by: Alyssa Ross <hi@alyssa.is>
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
Co-authored-by: Rick van Schijndel <Mindavi@users.noreply.github.com>
