Fix compile errors with GCC 4.2.
    
    gold/
    	PR gold/21040
    	* x86_64.cc (Output_data_plt_x86_64_bnd::do_fill_first_plt_entry):
    	Remove unnecessary 'typename' keyword.
    	(Output_data_plt_x86_64_bnd::do_fill_plt_entry): Likewise.
    	(Output_data_plt_x86_64_bnd::do_fill_tlsdesc_entry): Likewise.
    	(Output_data_plt_x86_64_bnd::fill_aplt_entry): Likewise.
    	* testsuite/copy_test_relro_1.cc (p, b, c, q): Add separate extern
    	declarations.