[rebase] Add SEH personality stubs (unused)

Author: alexcrichton

src/libstd/rt/unwind/seh.rs

@@ -19,3 +19,10 @@ pub unsafe fn panic(_data: Box<Any + Send + 'static>) -> ! {
 pub unsafe fn cleanup(_ptr: *mut c_void) -> Box<Any + Send + 'static> {
     intrinsics::abort();
 }
+
+#[lang = "eh_personality"]
+#[no_mangle]
+pub extern fn rust_eh_personality() {}
+
+#[no_mangle]
+pub extern fn rust_eh_personality_catch() {}