Implement speculative call verifier

Implement speculative call verifier

this patch implements verifier and fixes one bug where speculative calls
produced by ipa-devirt ended up having num_speculative_call_targets = 0
instead of 1.

	* cgraph.c (cgraph_edge::make_speculative): Increase number of
	speculative targets.
	(verify_speculative_call): New function
	(cgraph_node::verify_node): Use it.
	* ipa-profile.c (ipa_profile): Fix formating; do not set number of
	speculations.