use unique_ptr instead of constructor/destructor in benchmarks

On Windows static builds, destructors are invoked after the UMF destructor,
causing parameter structures to be unable to be destroyed. By switching to
std::unique_ptr, we ensure that parameters are properly cleaned up and
the destruction order issue is resolved.

Author: lplewa

benchmark/benchmark.cpp

@@ -48,11 +48,9 @@ struct os_provider : public provider_interface {
 
         // Use a lambda as the custom deleter
         auto deleter = [](void *p) {
-            if (p) {
-                auto handle =
-                    static_cast<umf_os_memory_provider_params_handle_t>(p);
-                umfOsMemoryProviderParamsDestroy(handle);
-            }
+            auto handle =
+                static_cast<umf_os_memory_provider_params_handle_t>(p);
+            umfOsMemoryProviderParamsDestroy(handle);
         };
 
         return {static_cast<void *>(raw_params), deleter};
@@ -120,12 +118,9 @@ struct disjoint_pool : public pool_interface<Provider> {
             return {nullptr, [](void *) {}};
         }
 
-        // Use a lambda as the deleter
         auto deleter = [](void *p) {
-            if (p) {
-                umfDisjointPoolParamsDestroy(
-                    static_cast<umf_disjoint_pool_params_handle_t>(p));
-            }
+            umfDisjointPoolParamsDestroy(
+                static_cast<umf_disjoint_pool_params_handle_t>(p));
         };
 
         return {static_cast<void *>(raw_params), deleter};