SARIF output: fix diagnostics within C++ member fns [PR122626]

SARIF output: fix diagnostics within C++ member fns [PR122626]

When building hierarchical logical locations, we were stopping traveral
upwards before any TRANSLATION_UNIT_DECL for decls, but not for types,
leading to an assertion failure when producing SARIF output for
diagnostics within C++ member fns.

Fixed thusly.

gcc/testsuite/ChangeLog:
	PR analyzer/122626
	* g++.dg/analyzer/malloc.C: Add sarif output to verify the fix for
	PR analyzer/122626.

gcc/ChangeLog:
	PR analyzer/122626
	* tree-logical-location.cc
	(tree_logical_location_manager::get_parent): Return null when
	TYPE_CONTEXT is a TRANSLATION_UNIT_DECL so that we don't fail
	the assertion in assert_valid_tree.

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