Fix travis config

.travis.yml

@@ -14,6 +14,7 @@ before_script:
 script:
   - cargo build --verbose
   - cargo test --verbose
+  - cargo test --verbose --features parallel
   - cargo test --manifest-path gcc-test/Cargo.toml --target $TARGET
   - cargo test --manifest-path gcc-test/Cargo.toml --target $TARGET --features parallel
   - cargo test --manifest-path gcc-test/Cargo.toml --target $TARGET --release

appveyor.yml

@@ -29,5 +29,7 @@ build: false
 
 test_script:
   - cargo test
+  - cargo test --features parallel
   - cargo test --manifest-path gcc-test/Cargo.toml
+  - cargo test --manifest-path gcc-test/Cargo.toml --features parallel
   - cargo test --manifest-path gcc-test/Cargo.toml --release

gcc-test/Cargo.toml

@@ -11,3 +11,6 @@ test = false
 
 [build-dependencies]
 gcc = { path = ".." }
+
+[features]
+parallel = ["gcc/parallel"]