Summary:
If you have built the `eden/scm` subdirectory with `make local` in your
repository it will have left a bunch of build output artifacts in the source
tree.  Update the getdeps shipit path map for eden to explicitly exclude many
of these build artifacts.

In particular:
- Exclude `eden/scm/build/` since this directory can contains a lot of files.
- Exclude all `*.pyc` files since there may be a reasonable number of these.
- Exclude several Cargo-related files since these will cause problems when
  trying to build Rust code.

Reviewed By: chadaustin

Differential Revision: D20570720

fbshipit-source-id: a60dec4854ae470fdb58e9651fd8a3b910c76004