Mark symbols in offload tables with force_output in read_offload_tables

Mark symbols in offload tables with force_output in read_offload_tables

2016-01-14  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/68773
	* c-parser.c (c_parser_oacc_declare, c_parser_omp_declare_target): Don't
	set force_output.

	* parser.c (cp_parser_oacc_declare, cp_parser_omp_declare_target): Don't
	set force_output.

	* omp-low.c (expand_omp_target): Don't set force_output.
	* varpool.c (varpool_node::get_create): Same.
	* lto-cgraph.c (input_offload_tables): Mark entries in offload_vars and
	offload_funcs with force_output.

From-SVN: r232384