test_features.sh: re-enable as a simple build

.travis.yml

@@ -6,6 +6,7 @@ rust:
 sudo: false
 script:
   - make test
+  - .travis/test_features.sh
   - |
     [ $TRAVIS_RUST_VERSION != nightly ] || .travis/test_nightly.sh
   - cargo doc

.travis/test_features.sh

@@ -3,5 +3,5 @@
 set -ex
 
 for feature in '' bigint rational complex; do
-  cargo test --verbose --no-default-features --features="$feature"
+  cargo build --verbose --no-default-features --features="$feature"
 done

src/lib.rs

@@ -97,6 +97,7 @@ use std::ops::{Mul};
 
 #[cfg(feature = "num-bigint")]
 pub use num_bigint as bigint;
+#[cfg(feature = "num-complex")]
 pub use num_complex as complex;
 pub use num_integer as integer;
 pub use num_iter as iter;