analyzer: fix further overzealous state purging [PR108733]

analyzer: fix further overzealous state purging [PR108733]

PR analyzer/108733 reports various false positives in qemu from
-Wanalyzer-use-of-uninitialized-value with __attribute__((cleanup))
at -O1 and above.

Root cause is that the state-purging code was failing to treat:
   _25 = MEM[(void * *)&val];
as a usage of "val", leading to it erroneously purging the
initialization of "val" along an execution path that didn't otherwise
use "val", apart from the  __attribute__((cleanup)).

Fixed thusly.

Integration testing on the patch show this change in the number of
diagnostics:
  -Wanalyzer-use-of-uninitialized-value
       coreutils-9.1: 18 -> 16 (-2)
          qemu-7.2.0: 87 -> 80 (-7)
where all that I investigated appear to have been false positives, hence
an improvement.

gcc/analyzer/ChangeLog:
	PR analyzer/108733
	* state-purge.cc (get_candidate_for_purging): Add ADDR_EXPR
	and MEM_REF.

gcc/testsuite/ChangeLog:
	PR analyzer/108733
	* gcc.dg/analyzer/torture/uninit-pr108733.c: New test.

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