Fixed iOS build (statics name lint)

src/libstd/rand/os.rs

@@ -88,6 +88,7 @@ pub struct OsRng {
     #[repr(C)]
     struct SecRandom;
 
+    #[allow(non_uppercase_statics)]
     static kSecRandomDefault: *const SecRandom = 0 as *const SecRandom;
 
     #[link(name = "Security", kind = "framework")]