add some new tests

Author: nikomatsakis

src/test/compile-fail/native-unsafe-fn-called.rs

@@ -0,0 +1,11 @@
+// -*- rust -*-
+// error-pattern: safe function calls function marked unsafe
+
+native "cdecl" mod test {
+    unsafe fn free();
+}
+
+fn main() {
+    test::free();
+}
+

src/test/compile-fail/native-unsafe-fn.rs

@@ -0,0 +1,12 @@
+// -*- rust -*-
+// error-pattern: unsafe functions can only be called
+
+native "cdecl" mod test {
+    unsafe fn free();
+}
+
+fn main() {
+    let x = test::free;
+}
+
+

src/test/compile-fail/unsafe-fn-called-from-safe.rs

@@ -1,6 +1,5 @@
 // -*- rust -*-
 // error-pattern: safe function calls function marked unsafe
-// xfail-test
 
 unsafe fn f() { ret; }