tree-optimization/99523 - missing SSA decls in dumps

tree-optimization/99523 - missing SSA decls in dumps

This makes sure to dump SSA names without identifier in the
declaration part of a function dump.  While we dump the
anonymous variable decls the SSA names referencing them appear
without a clear reference as to what anonymous variable is used
(_3 vs. D.1234).

2021-03-11  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/99523
	* tree-cfg.c (dump_function_to_file): Dump SSA names
	w/o identifier to the decls section as well, not only those
	without a VAR_DECL.