Make ssa_cache and ssa_lazy_cache virtual.

Make ssa_cache and ssa_lazy_cache virtual.

Making them virtual allows us to interchangebly use the caches.

	* gimple-range-cache.cc (ssa_cache::dump): Use get_range.
	(ssa_cache::dump_range_query): Delete.
	(ssa_lazy_cache::dump_range_query): Delete.
	(ssa_lazy_cache::get_range): Move from header file.
	(ssa_lazy_cache::clear_range): ditto.
	(ssa_lazy_cache::clear): Ditto.
	* gimple-range-cache.h (class ssa_cache): Virtualize.
	(class ssa_lazy_cache): Inherit and virtualize.