[PATCH] Add support for '-z global'

[Cary Coutant]

>>> +2014-11-19  Dimitry Ivanov <dimitry@google.com>
>>> +
>>> +       * layout.cc (Layout::finish_dynamic_section): When '-z global'
>>> +       is specified set DF_1_GLOBAL in DT_FLAGS_1 flags.
>>> +       * options.h (General_options): New -z option (global).

I've committed this gold patch on Dmitry's behalf.

-cary