Implement streamer for frange.

Implement streamer for frange.

This patch Allows us to export floating point ranges into the SSA name
(SSA_NAME_RANGE_INFO).

[Richi, in PR24021 you suggested that match.pd could use global float
ranges, because it would generally not invoke ranger.  This patch
implements the boiler plate to save the frange globally.]

[Jeff, we've also been talking in parallel of using NAN knowledge
during expansion to RTL.  This patch will provide the NAN bits in the
SSA name.]

Since frange's currently implementation is just a shell, with no
actual endpoints, frange_storage_slot only contains frange_props which
fits inside a byte.  When we have endpoints, y'all can decide if it's
worth saving them, or if the NAN/etc bits are good enough.

gcc/ChangeLog:

	* tree-core.h (struct tree_ssa_name): Add frange_info and
	reshuffle the rest.
	* value-range-storage.cc (vrange_storage::alloc_slot): Add case
	for frange.
	(vrange_storage::set_vrange): Same.
	(vrange_storage::get_vrange): Same.
	(vrange_storage::fits_p): Same.
	(frange_storage_slot::alloc_slot): New.
	(frange_storage_slot::set_frange): New.
	(frange_storage_slot::get_frange): New.
	(frange_storage_slot::fits_p): New.
	* value-range-storage.h (class frange_storage_slot): New.