analyzer: implement __analyzer_dump_escaped

PR analyzer/103546 seems to involve an issue in how the analyzer
tracks which decls have escaped, so this patch adds a way to directly
test this from DejaGnu.

gcc/analyzer/ChangeLog:
	* region-model-impl-calls.cc (cmp_decls): New.
	(cmp_decls_ptr_ptr): New.
	(region_model::impl_call_analyzer_dump_escaped): New.
	* region-model.cc (region_model::on_stmt_pre): Handle
	__analyzer_dump_escaped.
	* region-model.h (region_model::impl_call_analyzer_dump_escaped):
	New decl.
	* store.h (binding_cluster::get_base_region): New accessor.

gcc/ChangeLog:
	* doc/analyzer.texi
	(Special Functions for Debugging the Analyzer): Document
	__analyzer_dump_escaped.

gcc/testsuite/ChangeLog:
	* gcc.dg/analyzer/analyzer-decls.h (__analyzer_dump_escaped): New
	decl.
	* gcc.dg/analyzer/escaping-1.c: New test.