Ensure it builds in nostd

Author: roblabla

.travis.yml

@@ -10,6 +10,7 @@ matrix:
 script:
   - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo test --verbose --all-features; fi
   - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo bench --verbose --all-features --no-run; fi
+  - if [[ "$TRAVIS_NIGHTLY" == "true" ]]; then cargo build --verbose --no-default-features --target thumbv7m-none-eabi; fi
   - if [[ "$TRAVIS_NIGHTLY" != "true" ]]; then cargo test --verbose; fi
 
 cache: cargo