Enable cross compile to android from mac.

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 31 matching lines @@
     } else if (use_ccache) {
       compiler_prefix = "ccache "
     } else {
       compiler_prefix = ""
     }
 
     cc = compiler_prefix + tool_prefix + "gcc"
     cxx = compiler_prefix + tool_prefix + "g++"
     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}}"
 
     stripped_soname = "lib.stripped/${soname}"
     temp_stripped_soname = "${stripped_soname}.tmp"
@@ skipping 58 matching lines @@
   toolchain_cpu = "aarch64"
 }
 
 android_gcc_toolchain("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"
 }