analyzer: fix ICE getting void return value (PR 93379)

analyzer: fix ICE getting void return value (PR 93379)

PR analyzer/93379 reports an ICE within
region_model::update_for_return_superedge when writing the
returned svalue_id to the lhs of the call_stmt

The root cause is that this analyzer code assumed that for any call
with a non-NULL gimple_call_lhs, the called fndecl would have non-void
return type, and thus that a non-null svalue_id would be returned from
region_model::pop_frame.  This isn't the case e.g. for a call with
conflicting types where the callee returns void but the caller assumes
int.

This patch fixes the ICE by moving the check for null result so that
it also guards setting the lhs.

gcc/analyzer/ChangeLog:
	PR analyzer/93379
	* region-model.cc (region_model::update_for_return_superedge):
	Move check for null result so that it also guards setting the
	lhs.

gcc/testsuite/ChangeLog:
	PR analyzer/93379
	* gcc.dg/analyzer/torture/pr93379-2.c: New test.
	* gcc.dg/analyzer/torture/pr93379.c: New test.