Update clippy

Cargo.lock

@@ -487,7 +487,7 @@ dependencies = [
  "regex-syntax",
  "semver",
  "serde",
- "smallvec 0.6.10",
+ "smallvec 1.0.0",
  "toml",
  "unicode-normalization",
  "url 2.1.0",

src/bootstrap/test.rs

@@ -570,7 +570,12 @@ impl Step for Clippy {
             let host_libs = builder
                 .stage_out(compiler, Mode::ToolRustc)
                 .join(builder.cargo_dir());
+            let target_libs = builder
+                .stage_out(compiler, Mode::ToolRustc)
+                .join(&self.host)
+                .join(builder.cargo_dir());
             cargo.env("HOST_LIBS", host_libs);
+            cargo.env("TARGET_LIBS", target_libs);
             // clippy tests need to find the driver
             cargo.env("CLIPPY_DRIVER_PATH", clippy);