ensure rand has its default features enabled

Cargo.lock

@@ -3098,6 +3098,7 @@ dependencies = [
  "bstr 0.2.17",
  "clap 3.2.20",
  "libz-sys",
+ "rand 0.8.5",
  "regex",
  "serde_json",
  "syn",

src/tools/rustc-workspace-hack/Cargo.toml

@@ -82,6 +82,8 @@ regex = { version = "1.5.6" }
 serde_json = { version = "1.0.31", features = ["raw_value", "unbounded_depth"] }
 syn = { version = "1", features = ['full', 'visit'] }
 url = { version = "2.0", features = ['serde'] }
+# Ensure default features of rand, which are disabled in some scenarios.
+rand = { version = "0.8.5" }
 
 [target.'cfg(not(windows))'.dependencies]
 openssl = { version = "0.10.35", optional = true }