analyzer: fix ICE on zero-arg calls passed to __attribute__((nonnull)) [PR 99906]

analyzer: fix ICE on zero-arg calls passed to __attribute__((nonnull)) [PR 99906]

gcc/analyzer/ChangeLog:
	PR analyzer/99906
	* analyzer.cc (maybe_reconstruct_from_def_stmt): Fix NULL
	dereference on calls with zero arguments.
	* sm-malloc.cc (malloc_state_machine::on_stmt): When handling
	__attribute__((nonnull)), only call get_diagnostic_tree if the
	result will be used.

gcc/testsuite/ChangeLog:
	PR analyzer/99906
	* gcc.dg/analyzer/pr99906.c: New test.