Fix for building ARM/linux using clang.

src/trusted/service_runtime/linux/nacl_bootstrap.gyp

 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'includes': [
     '../../../../build/common.gypi',
   ],
   'conditions': [
     ['target_arch=="x64"', {
@@ skipping 167 matching lines @@
             # set at gyp time. This is a hacky way to bake the correct
             # CXX into the build at gyp time.
             # TODO(sbc): Do this better by providing some gyp syntax
             # for accessing the name of the configured compiler, or
             # even a better way to access gyp time environment
             # variables from within a gyp file.
             ['OS=="android"', {
               'variables': {
                 'compiler': '<!(/bin/echo -n <(android_toolchain)/*-g++)',
               }
+            }],
+            ['OS!="android" and target_arch=="arm"', {
+              'variables': {
+                'compiler': '<!(echo ${CXX:=arm-linux-gnueabi-g++})',

[Mark Seaborn, 2014/07/23 19:13:41]

I don't understand this part of the change.  Can you explain?

[Sam Clegg, 2014/07/23 19:21:52]

This action needs access to the target linker.  I'm can't remember exactly why.

Previously we were setting $CXX when cross compiling.  Now we are using clang
with a "-target" argument, so CXX is not set.  What is more g++ (the default) or
clang where would both give the wrong result as they would default to host
builds.

I admit that this is pretty horrible.  Perhaps there is some
way we can avoid this action.  I will investigate.

+              }
             }, {
               'variables': {
                 'compiler': '<!(echo ${CXX:=g++})',
               }
             }],
           ],
           'action': ['python', 'ld_bfd.py',
                      '--compiler', '<(compiler)',
                      '-m', '<(linker_emulation)',
                      '--build-id',
@@ skipping 37 matching lines @@
         'inputs': ['nacl_bootstrap_munge_phdr.py',
                    '<(PRODUCT_DIR)/nacl_bootstrap_munge_phdr',
                    '<(PRODUCT_DIR)/nacl_bootstrap_raw'],
         'outputs': ['<(PRODUCT_DIR)/nacl_helper_bootstrap'],
         'message': 'Munging ELF program header',
         'action': ['python', '<@(_inputs)', '<@(_outputs)']
       }],
     },
   ],
 }