Enable clippy in CI.

Author: m-ou-se

ci/script.sh

@@ -31,6 +31,11 @@ main() {
     if [ $TARGET = x86_64-unknown-linux-gnu ]; then
         ./check-blobs.sh
     fi
+
+    if [ $TRAVIS_RUST_VERSION = nightly ]; then
+        rustup component add clippy
+        cargo clippy --target $TARGET
+    fi
 }
 
 main