libstrat: enable -Wextra, -Werror

This caught an embarrassingly large number of bugs.

libraries/libstratosphere/source/sf/sf_default_allocation_policy.cpp

@@ -70,10 +70,12 @@ namespace ams::sf {
         constinit DefaultAllocatorImpl g_default_allocator_impl = {};
 
         inline void *DefaultAllocate(size_t size, size_t align) {
+            AMS_UNUSED(align);
             return ::operator new(size, std::nothrow);
         }
 
         inline void DefaultDeallocate(void *ptr, size_t size, size_t align) {
+            AMS_UNUSED(size, align);
             return ::operator delete(ptr, std::nothrow);
         }