Fix compat with older Rust

Close #120

.travis.yml

@@ -3,6 +3,12 @@ rust:
   - stable
   - beta
   - nightly
+matrix:
+  include:
+    # Minimum version supported
+    - rust: 1.6.0
+      script: cargo build
+
 sudo: false
 install:
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then OS=unknown-linux-gnu; else OS=apple-darwin; fi

src/lib.rs

@@ -356,7 +356,7 @@ impl Config {
         if self.get_target().contains("msvc") {
             let compiler = self.get_base_compiler();
             let atlmfc_lib = compiler.env().iter().find(|&&(ref var, _)| {
-                var == OsStr::new("LIB")
+                var.as_os_str() == OsStr::new("LIB")
             }).and_then(|&(_, ref lib_paths)| {
                 env::split_paths(lib_paths).find(|path| {
                     let sub = Path::new("atlmfc/lib");