fix(svt-av1): fix build error on mingw

packages/s/svt-av1/xmake.lua

@@ -35,6 +35,8 @@ package("svt-av1")
             io.replace("CMakeLists.txt", "set(CMAKE_EXE_LINKER_FLAGS \"${CMAKE_EXE_LINKER_FLAGS} -z noexecstack -z relro -z now\")",  "", {plain = true})
             io.replace(path.join(os.curdir(), "Source", "Lib", "Decoder", "CMakeLists.txt"), "list(APPEND PLATFORM_LIBS Threads::Threads)", "", {plain = true})
             io.replace(path.join(os.curdir(), "Source", "Lib", "Encoder", "CMakeLists.txt"), "list(APPEND PLATFORM_LIBS Threads::Threads)", "", {plain = true})
+        elseif package:is_plat("mingw") and package:is_arch("x64", "x86_64") then
+            table.insert(configs, "-DCMAKE_SYSTEM_PROCESSOR=AMD64")
         end
         import("package.tools.cmake").install(package, configs)
     end)