Update sample workload wasm-av1 and add workload XNNPACK (#443)

samples/workload/XNNPACK/toolchain/BUILD.bazel

@@ -0,0 +1,30 @@
+# Copyright (C) 2019 Intel Corporation. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+package(default_visibility = ['//visibility:public'])
+
+load(":emscripten_toolchain_config.bzl", "emsdk_toolchain_config")
+
+cc_toolchain_suite(
+  name = "emscripten",
+  toolchains = {
+    "wasm": ":emsdk_toolchain",
+  },
+)
+
+filegroup(name = "empty")
+
+emsdk_toolchain_config(name = "emsdk_toolchain_config")
+
+cc_toolchain(
+    name = "emsdk_toolchain",
+    toolchain_identifier = "emsdk-toolchain",
+    toolchain_config = ":emsdk_toolchain_config",
+    all_files = ":empty",
+    compiler_files = ":empty",
+    dwp_files = ":empty",
+    linker_files = ":empty",
+    objcopy_files = ":empty",
+    strip_files = ":empty",
+    supports_param_files = 0,
+)