Add some skip flags

Author: JohnTitor

src/test/codegen/ffi-out-of-bounds-loads.rs

@@ -1,6 +1,9 @@
-// compile-flags: -C no-prepopulate-passes
 // Regression test for #29988
 
+// compile-flags: -C no-prepopulate-passes
+// only-x86_64
+// ignore-windows
+
 #[repr(C)]
 struct S {
     f1: i32,