Add gcc_assert that &global_options are not dirty modified.

Add gcc_assert that &global_options are not dirty modified.

gcc/ChangeLog:

2020-03-20  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/92860
	* optc-save-gen.awk: Generate new function cl_optimization_compare.
	* opth-gen.awk: Generate declaration of the function.

gcc/c-family/ChangeLog:

2020-03-20  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/92860
	* c-attribs.c (handle_optimize_attribute):
	Save global options and compare it after parsing of function
	attribute.
	* c-pragma.c (opt_stack::saved_global_options): New field.
	(handle_pragma_push_options): Save global_options.
	(handle_pragma_pop_options): Compare them after pop.