Fix for latest rust-master
Merge pull request #48 from am0d/master

Fix for latest rust-master
Fix a couple of privacy errors.

A bug in Rust had caused these to work hitherto despite being private.
Makefile: produce both a dynamic library and an .rlib, this is overridable
Change pkgid to crate_id (upstream change).
Merge pull request #49 from Blei/libflags

Makefile: produce both a dynamic library and an .rlib, this is overridable
Remove obsolete link attribute
Merge pull request #50 from eholk/fixes

Remove obsolete link attribute
Stop using Either, removed in mozilla/rust#11149