analyzer: fix clang warnings [PR112317]

analyzer: fix clang warnings [PR112317]

No functional change intended.

gcc/analyzer/ChangeLog:
	PR analyzer/112317
	* access-diagram.cc (class x_aligned_x_ruler_widget): Eliminate
	unused field "m_col_widths".
	(access_diagram_impl::add_valid_vs_invalid_ruler): Update for
	above change.
	* region-model.cc
	(check_one_function_attr_null_terminated_string_arg): Remove
	unused variables "cd_unchecked", "strlen_sval", and
	"limited_sval".
	* region-model.h (region_model_context_decorator::warn): Add
	missing "override".

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