Simple bug fix in gold linker.

[Ian Lance Taylor]

Sriraman Tallam <tmsriram@google.com> writes:

>    Patch ok? This was causing an uninitialized variable error while building.
>
> 	* symtab.cc (Symbol_table::add_undefined_symbol_from_command_line):
> 	Initialize oldsym to prevent uninitialized variable errors.

Instead of this, change Symbol_table::define_special_symbol to set
*poldsym = NULL at the top of the function.  That patch is approved if
it fixes the problem.

Ian