diagnostic.c: Don't include plugin.h.

diagnostic.c: Don't include plugin.h.

	* diagnostic.c: Don't include plugin.h.
	(diagnostic_report_diagnostic): Don't handle plugins specially
	here.  Pass context to internal_error callback.
	* diagnostic.h (struct diagnostic_context): Add context parameter
	to internal_error callback.
	* plugin.c (warn_if_plugins, plugins_internal_error_function):
	New.
	* plugin.h (struct diagnostic_context): Declare.
	(warn_if_plugins, plugins_internal_error_function): Declare.
	* toplev.c (general_init): Set global_dc->internal_error.
	* Makefile.in (diagnostic.o): Update dependencies.

ada:
	* gcc-interface/misc.c (internal_error_function): Add context
	parameter.  Use it to access show_column flag and instead of using
	global_dc.  Call warn_if_plugins.
	* gcc-interface/Make-lang.in (ada/misc.o): Update dependencies.

From-SVN: r159819