libstrat: fix compilation without pre-compiled header/without lto

libraries/libstratosphere/include/stratosphere/fssystem/fssystem_indirect_storage.hpp

@@ -142,10 +142,12 @@ namespace ams::fssystem {
             }
 
             virtual Result Write(s64 offset, const void *buffer, size_t size) override {
+                AMS_UNUSED(offset, buffer, size);
                 return fs::ResultUnsupportedOperationInIndirectStorageA();
             }
 
             virtual Result SetSize(s64 size) override {
+                AMS_UNUSED(size);
                 return fs::ResultUnsupportedOperationInIndirectStorageB();
             }
         protected: