Vendor dependencies

Let's see how I like this workflow.

vendor/num_cpus/Cargo.lock

@@ -0,0 +1,26 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "hermit-abi"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "307c3c9f937f38e3534b1d6447ecf090cafcc9744e4a6360e8b037b2cf5af120"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a31a0627fdf1f6a39ec0dd577e101440b7db22672c0901fe00a9a6fbb5c24e8"
+
+[[package]]
+name = "num_cpus"
+version = "1.14.0"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]