analyzer: fix ICE on bogus decl of memset [PR97130]

analyzer: fix ICE on bogus decl of memset [PR97130]

Verify that arguments are pointers before calling handling code
that calls deref_rvalue on them.

gcc/analyzer/ChangeLog:
	PR analyzer/97130
	* region-model-impl-calls.cc (call_details::get_arg_type): New.
	* region-model.cc (region_model::on_call_pre): Check that the
	initial arg is a pointer before calling impl_call_memset and
	impl_call_strlen.
	* region-model.h (call_details::get_arg_type): New decl.

gcc/testsuite/ChangeLog:
	PR analyzer/97130
	* gcc.dg/analyzer/pr97130.c: New test.