[interop][SwiftToCxx] NFC, test remove unused warning flag

Author: hyp

test/Interop/SwiftToCxx/generics/generic-struct-in-cxx.swift

@@ -1,16 +1,16 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend %s -typecheck -module-name Generics -clang-header-expose-public-decls -emit-clang-header-path %t/generics.h
 // RUN: %FileCheck %s < %t/generics.h
-// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h -Wno-unused-function)
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h)
 
 // Check that an instantiation compiles too.
 // RUN: echo "constexpr int x = sizeof(Generics::GenericPair<int, int>);" >> %t/generics.h
-// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h -Wno-unused-function)
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h)
 
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend %s -enable-library-evolution -typecheck -module-name Generics -clang-header-expose-public-decls -emit-clang-header-path %t/generics.h
 // RUN: %FileCheck %s < %t/generics.h
-// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h -Wno-unused-function)
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/generics.h)
 
 @frozen
 public struct GenericPair<T, T2> {