Add i686 to travis

.travis.yml

@@ -22,6 +22,18 @@ matrix:
       env:
         - TEST=crash
         - RUST_BACKTRACE=1
+    - rust: nightly-2018-01-02
+      env:
+        - TEST=cross-build
+        - TARGET=i686-unknown-linux-gnu
+
+install:
+  - curl https://sh.rustup.rs -sSf |
+    sh -s -- -y --default-toolchain $TRAVIS_RUST_VERSION
+  - if [ -n "$TARGET" ]; then
+        rustup target add $TARGET;
+    fi
+  - source ~/.cargo/env
 
 script:
   - bash -c 'case "$TEST" in
@@ -38,6 +50,11 @@ script:
                crash)
                  cargo test test_crash_recovery --release --features="check_snapshot_integrity" -- --nocapture
                  ;;
+               cross-build)
+                 echo "https://github.com/rust-lang/cargo/issues/4753"
+                 pushd crates/sled; cargo build --target $TARGET --features=nightly; popd;
+                 pushd crates/pagecache; cargo build --target $TARGET --features=nightly; popd;
+                 ;;
                *)
                  cargo check;
                  cargo check --features=all;