analyzer: handle symbolic bindings in scan_for_null_terminator [PR105899]

analyzer: handle symbolic bindings in scan_for_null_terminator [PR105899]

gcc/analyzer/ChangeLog:
	PR analyzer/105899
	* region-model.cc (iterable_cluster::iterable_cluster): Add
	symbolic binding keys to m_symbolic_bindings.
	(iterable_cluster::has_symbolic_bindings_p): New.
	(iterable_cluster::m_symbolic_bindings): New field.
	(region_model::scan_for_null_terminator): Treat clusters with
	symbolic bindings as having unknown strlen.

gcc/testsuite/ChangeLog:
	PR analyzer/105899
	* gcc.dg/analyzer/sprintf-1.c: Include "analyzer-decls.h".
	(test_strlen_1): New.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>