Use this source map method for assigning a location to any entity whose
source number is not exposed. This could be
- Instructions.
- Signatures defined implicitly by function decls.
These entities only appear in the location map, not the entity number
maps.
Give these crates each a more standard directory layout with sources in
a 'src' sub-sirectory and Cargo.toml in the top lib/foo directory.
Add license and description fields to each.
The build script for the cretonne crate now lives in
'lib/cretonne/build.rs' separating it from the normal library sources
under 'lib/cretonne/src'.
