Vendor dependencies

Let's see how I like this workflow.

vendor/num_cpus/Cargo.toml

@@ -0,0 +1,32 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+name = "num_cpus"
+version = "1.14.0"
+authors = ["Sean McArthur <sean@seanmonstar.com>"]
+description = "Get the number of CPUs on a machine."
+documentation = "https://docs.rs/num_cpus"
+readme = "README.md"
+keywords = [
+    "cpu",
+    "cpus",
+    "cores",
+]
+categories = ["hardware-support"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/seanmonstar/num_cpus"
+
+[target."cfg(all(any(target_arch = \"x86_64\", target_arch = \"aarch64\"), target_os = \"hermit\"))".dependencies.hermit-abi]
+version = "0.1.3"
+
+[target."cfg(not(windows))".dependencies.libc]
+version = "0.2.26"