[infra] Roll clang to match the version used by Flutter

build/toolchain/android/BUILD.gn

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sysroot.gni")  # Imports android/config.gni.
 import("//build/toolchain/ccache.gni")
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
@@ skipping 29 matching lines @@
       assert(!use_ccache, "Goma and ccache can't be used together.")
       compiler_prefix = "$goma_dir/gomacc "
     } else if (use_ccache) {
       compiler_prefix = "ccache "
     } else {
       compiler_prefix = ""
     }
 
     is_clang = invoker.is_clang
     if (is_clang) {
-      prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
+      host_suffix = ""
+      if (host_os == "linux") {
+        host_suffix = "x86_64-linux"
+      } else if (host_os == "mac") {
+        host_suffix = "x86_64-darwin"
+      } else {
+        assert(false, "Unknown host")
+      }
+
+      prefix = rebase_path("//buildtools/toolchain/clang+llvm-$host_suffix/bin",
                            root_build_dir)
 
       cc = compiler_prefix + prefix + "/clang"
       cxx = compiler_prefix + prefix + "/clang++"
+      ar = prefix + "/llvm-ar"
     } else {
       cc = compiler_prefix + tool_prefix + "gcc"
       cxx = compiler_prefix + tool_prefix + "g++"
+      ar = tool_prefix + "ar"
     }
 
-    ar = tool_prefix + "ar"
     ld = cxx
     readelf = compiler_prefix + tool_prefix + "readelf"
     nm = compiler_prefix + tool_prefix + "nm"
 
     toolchain_os = "android"
     toolchain_cpu = invoker.toolchain_cpu
 
     # We make the assumption that the gcc_toolchain will produce a soname with
     # the following definition.
     soname = "{{target_output_name}}{{output_extension}}"
@@ skipping 75 matching lines @@
   toolchain_cpu = "aarch64"
 }
 
 android_gcc_toolchains_helper("mips64el") {
   android_ndk_sysroot = "$android_ndk_root/$mips64_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib64"
 
   tool_prefix = "$mips64_android_toolchain_root/bin/mipsel-linux-android-"
   toolchain_cpu = "mipsel64el"
 }