ipa: Introduce ipa_cached_call_context

ipa: Introduce ipa_cached_call_context

Hi,

as we discussed with Honza on the mailin glist last week, making
cached call context structure distinct from the normal one may make it
clearer that the cached data need to be explicitely deallocated.

This patch does that division.  It is not mandatory for the overall
main goals of the patch set and can be dropped if deemed superfluous.

gcc/ChangeLog:

2020-09-02  Martin Jambor  <mjambor@suse.cz>

	* ipa-fnsummary.h (ipa_cached_call_context): New forward declaration
	and class.
	(class ipa_call_context): Make friend ipa_cached_call_context.  Moved
	methods duplicate_from and release to it too.
	* ipa-fnsummary.c (ipa_call_context::duplicate_from): Moved to class
	ipa_cached_call_context.
	(ipa_call_context::release): Likewise, removed the parameter.
	* ipa-inline-analysis.c (node_context_cache_entry): Change the type of
	ctx to ipa_cached_call_context.
	(do_estimate_edge_time): Remove parameter from the call to
	ipa_cached_call_context::release.