* opts-common.c (handle_option, handle_generated_option,
	read_cmdline_option, set_option): Add diagnostic_context
	parameter.  Update calls among these functions.
	(set_option): Don't use global_dc.
	* opts.c (read_cmdline_options): Pass global_dc to
	read_cmdline_option.
	(decode_options): Pass global_dc to enable_warning_as_error.
	(common_handle_option): Pass global_dc to enable_warning_as_error.
	(enable_warning_as_error): Add diagnostic_context parameter.
	Document parameters.  Don't use global_dc.  Pass
	diagnostic_context parameter to handle_generated_option.
	* opts.h (set_option, handle_option, handle_generated_option,
	read_cmdline_option, enable_warning_as_error): Add
	diagnostic_context parameter.
	* Makefile.in (lto-opts.o): Update dependencies.
	* coretypes.h (struct diagnostic_context, diagnostic_context):
	Declare here.
	* diagnostic.h (diagnostic_context): Don't declare typedef here.
	* gcc.c (process_command): Pass global_dc to read_cmdline_option.
	* langhooks-def.h (struct diagnostic_context): Don't declare here.
	(lhd_print_error_function, lhd_initialize_diagnostics): Declare
	using diagnostic_context typedef.
	* langhooks.c (lhd_initialize_diagnostics): Declare using
	diagnostic_context typedef.
	* langhooks.h (struct diagnostic_context): Don't declare here.
	(initialize_diagnostics, print_error_function): Declare using
	diagnostic_context typedef.
	* lto-opts.c: Include diagnostic.h.
	(lto_reissue_options): Pass global_dc to set_option.  Pass
	DK_UNSPECIFIED not 0.
	* plugin.c (plugins_internal_error_function): Declare using
	diagnostic_context typedef.
	* plugin.h (struct diagnostic_context): Don't declare here.
	(plugins_internal_error_function): Declare using
	diagnostic_context typedef.

c-family:
	* c-common.h (struct diagnostic_context): Don't declare here.
	(c_common_initialize_diagnostics): Declare using
	diagnostic_context typedef.
	* c-opts.c (c_common_handle_option): Pass global_dc to
	handle_generated_option.

cp:
	* cp-tree.h (cxx_print_error_function,
	cxx_initialize_diagnostics): Declare using diagnostic_context
	typedef.

From-SVN: r164991