0.9.3: Prevent multiple copies of *ring* from being linked.

This will only protect against linking multiple copies of version from
0.9.3 onward; i.e. it won't prevent a version like 0.7.6 from being
linked alongside 0.9.3.

Author: briansmith

Cargo.toml

@@ -9,7 +9,10 @@ license-file = "LICENSE"
 name = "ring"
 readme = "README.md"
 repository = "https://github.com/briansmith/ring"
-version = "0.9.2"
+version = "0.9.3"
+
+# Prevent multiple versions of *ring* from being linked into the same program.
+links = "ring-asm"
 
 exclude = [
     # The presence of .gitignore is used to differentiate non-packaged builds