This bring RHEL rust-toolset in sync with the latest Fedora
rust-packaging, most importantly:
* Fedora's new style (-v vendor) vendoring is implemented. The old RHEL
style (-V #) vendoring is still supported, at least until we can convert
everything in ELN.
* Automatic generation of bundled provides using %cargo_vendor_manifest.
However, instead of depending on cargo2rpm, a very stripped-down version
of just its parse-vendor-manifest command is provided as a private
script, along with a fileattr to call it.
Other changes incorporated in this commit:
* -Cstrip=none added to %build_rustflags.
* --profile rpm is used instead of --release.
* Errors in spawned commands are now caught.
* Comments and whitespace are synced for easier comparison with Fedora.
* --target all is dropped from license and vendor macros, to avoid false
alarms from windows crates.
