Remove the criterion dependency and add comment to re-add it to run b…

…enchmarks.

We are forced to remove the dependency because of the Cargo bug rust-lang/cargo#4866 that would break compilation for #[no-std].

In practice, this means benchmarks will not compile any more unless we manually uncomment the criterion dependency.

Cargo.toml

@@ -54,9 +54,11 @@ alga = { git = "https://github.com/rustsim/alga", branch = "dev" }
 [dev-dependencies]
 serde_json = "1.0"
 rand_xorshift = "0.1"
-# Newer vesrion of criterion make the compilation with no-std fail.
-# This problem is partly due to https://github.com/rust-lang/cargo/issues/1796
-criterion = "=0.2.7"
+### Uncomment this line before running benchmarks.
+### We can't just let this uncommented because that would breack
+### compilation for #[no-std] because of the terrible Cargo bug
+### https://github.com/rust-lang/cargo/issues/4866
+#criterion = "0.2.10"
 
 [workspace]
 members = [ "nalgebra-lapack", "nalgebra-glm" ]