Rename "meta" back to "cranelift-codegen-meta" and publish it.

It appears that having the meta directory crate be inside the codegen
directory is not enough to allow codegen to depend on it without it
being published. So, let's just publish it.

lib/codegen/Cargo.toml

@@ -22,7 +22,7 @@ target-lexicon = { version = "0.0.3", default-features = false }
 # accomodated in `tests`.
 
 [build-dependencies]
-meta = { path = "meta", version = "0.0.0" }
+cranelift-codegen-meta = { path = "meta" }
 
 [features]
 # The "std" feature enables use of libstd. The "core" feature enables use