cargo_embargo: fix generation of rules.mk
In order to generate rules.mk for crates stored at paths containing
a hyphen, we keep the package name returned by cargo metadata around
such that we can use it when generating Trusty makefile rules.
Test: run `cargo_embargo generate cargo_embargo.json` in num-derive
with rules.mk generation enabled, check that path to dependent
crate proc-macro2 is external/rust/crates/proc-macro2
Bug: None
Change-Id: Ibbb4a48da70548dd9476e326b3da263eb8a87cb6
9 files changed
