Suppress -Wanalyzer-{possible}-null-deref in some address spaces [PR123981]

Suppress -Wanalyzer-{possible}-null-deref in some address spaces [PR123981]

gcc/analyzer/ChangeLog:
	PR analyzer/123981
	* sm-malloc.cc: Include "target.h".
	(zero_address_valid_p): New.
	(malloc_state_machine::on_stmt): Guard possible_null_deref and
	null_deref with !zero_address_valid_p.

gcc/testsuite/ChangeLog:
	PR analyzer/123981
	* gcc.dg/analyzer/null-deref-pr123981-1.c: New test.
	* gcc.dg/analyzer/null-deref-pr123981-2.c: New test.

Co-Authored-By: David Malcolm <dmalcolm@redhat.com>
Signed-off-by: Federico Angelilli <code@fedang.net>
Signed-off-by: David Malcolm <dmalcolm@redhat.com>