Disable run-pass/lib-io.rs on mac

src/test/run-pass/lib-io.rs

@@ -4,6 +4,8 @@
 import std::io;
 import std::str;
 
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "win32")]
 fn test_simple() {
     let str tmpfile = "test/run-pass/lib-io-test-simple.tmp";
     log tmpfile;
@@ -20,6 +22,10 @@ fn test_simple() {
     assert (str::eq(frood, frood2));
 }
 
+// FIXME (726)
+#[cfg(target_os = "macos")]
+fn test_simple() {}
+
 fn main() {
     test_simple();
 }