message: build.py: inherit environment in the gcc builder
  Summary:
  This should enable the compiler to find the system linker for the link
  step.
  Reviewers: stella.stamenova, zturner
  Subscribers: lldb-commits
diff: @@ -153,6 +153,9 @@ def format_text(lines, indent_0, indent_n):
  return result
  def print_environment(env):
  + if env is None:
  + print(' Inherited')
  + return
  for e in env:
  value = env[e]
  lines = value.split(os.pathsep)
  @@ -633,7 +636,7 @@ class GccBuilder(Builder):
  args.extend(['-o', obj])
  args.append(source)
  - return ('compiling', [source], obj, {}, args)
  + return ('compiling', [source], obj, None, args)
  def _get_link_command(self):
  args = []
  @@ -649,7 +652,7 @@ class GccBuilder(Builder):
  args.extend(['-o', self._exe_file_name()])
  args.extend(self._obj_file_names())
  - return ('linking', self._obj_file_names(), self._exe_file_name(), {}, args)
  + return ('linking', self._obj_file_names(), self._exe_file_name(), None, args)
  def output_files(self):
  