iphlpapi: Update the buffer size only if required in GetAdaptersAddresses.

dlls/iphlpapi/iphlpapi_main.c

@@ -1382,8 +1382,10 @@ ULONG WINAPI DECLSPEC_HOTPATCH GetAdaptersAddresses(ULONG family, ULONG flags, P
         ret = ERROR_SUCCESS;
     }
     else
+    {
         ret = ERROR_BUFFER_OVERFLOW;
-    *buflen = total_size;
+        *buflen = total_size;
+    }
 
     TRACE("num adapters %u\n", table->numIndexes);
     HeapFree(GetProcessHeap(), 0, table);

dlls/iphlpapi/tests/iphlpapi.c

@@ -1338,7 +1338,6 @@ static void test_GetAdaptersAddresses(void)
     ptr = HeapAlloc(GetProcessHeap(), 0, osize);
     ret = pGetAdaptersAddresses(AF_UNSPEC, 0, NULL, ptr, &osize);
     ok(!ret, "expected ERROR_SUCCESS got %u\n", ret);
-todo_wine
     ok(osize == size, "expected %d, got %d\n", size, osize);
 
     for (aa = ptr; !ret && aa; aa = aa->Next)