add cargo clippy runs to see if it can build successfully (rust-lang#143)

Author: Byron

ci/set_rust_version.bash

@@ -1,4 +1,4 @@
 #!/usr/bin/env bash
 set -e
 rustup default $1
-rustup target add $2
+rustup target add $2

ci/test.bash

@@ -67,4 +67,10 @@ set -x
 $CROSS test --features zlib --target $TARGET_TRIPLE
 $CROSS test --features zlib-default --no-default-features --target $TARGET_TRIPLE
 $CROSS test --features zlib-ng --no-default-features --target $TARGET_TRIPLE
-$CROSS test --features zlib-ng-compat --no-default-features --target $TARGET_TRIPLE
+$CROSS test --features zlib-ng-compat --no-default-features --target $TARGET_TRIPLE
+
+if rustup component list | grep clippy &>/dev/null; then
+  $CROSS clippy --features zlib-ng --no-default-features --target $TARGET_TRIPLE
+  $CROSS clippy --features zlib --target $TARGET_TRIPLE
+  $CROSS clippy --features zlib-default --no-default-features --target $TARGET_TRIPLE
+fi