Remove default constructors & assignment operators from UnusualSwiftcallStruct to allow aggregate initialization in C++20.

PiperOrigin-RevId: 509212653

rs_bindings_from_cc/test/function/calling_conventions/calling_conventions.h

diff --git a/rs_bindings_from_cc/test/function/calling_conventions/calling_conventions.h b/rs_bindings_from_cc/test/function/calling_conventions/calling_conventions.h
index 83f9a94..73da458 100644
--- a/rs_bindings_from_cc/test/function/calling_conventions/calling_conventions.h
+++ b/rs_bindings_from_cc/test/function/calling_conventions/calling_conventions.h
@@ -15,12 +15,6 @@
 // On most platforms structs that are 3 words or smaller are passed directly
 // in swiftcall.
 struct UnusualSwiftcallStruct final {
-  UnusualSwiftcallStruct() = default;
-  UnusualSwiftcallStruct(const UnusualSwiftcallStruct&) = default;
-  UnusualSwiftcallStruct(UnusualSwiftcallStruct&&) = default;
-  UnusualSwiftcallStruct& operator=(const UnusualSwiftcallStruct&) = default;
-  UnusualSwiftcallStruct& operator=(UnusualSwiftcallStruct&&) = default;
-
   uintptr_t x0, x1, x2;
 };