analyzer: eliminate region_model::eval_condition_without_cm [PR101962]

In r12-3094-ge82e0f149b0aba I added the assumption that
POINTER_PLUS_EXPR of non-NULL is non-NULL (for PR analyzer/101962).

Whilst working on another bug, I noticed that this only works
when the LHS is known to be non-NULL via
region_model::eval_condition_without_cm, but not when it's known through
a constraint.

This distinction predates the original commit of the analyzer in GCC 10,
but I believe it became irrelevant in the GCC 11 rewrite of the region
model code (r11-2694-g808f4dfeb3a95f).

Hence this patch eliminates region_model::eval_condition_without_cm in
favor of all users simply calling region_model::eval_condition.  Doing
so enables the "POINTER_PLUS_EXPR of non-NULL is non-NULL" assumption to
also be made when the LHS is known through a constraint (e.g. a
conditional).

gcc/analyzer/ChangeLog:
	PR analyzer/101962
	* region-model-impl-calls.cc: Update comment.
	* region-model.cc (region_model::check_symbolic_bounds): Fix
	layout of "void" return.  Replace usage of
	eval_condition_without_cm with eval_condition.
	(region_model::eval_condition): Take over body of...
	(region_model::eval_condition_without_cm): ...this subroutine,
	dropping the latter.  Eliminating this distinction avoids issues
	where constraints were not considered when recursing.
	(region_model::compare_initial_and_pointer): Update comment.
	(region_model::symbolic_greater_than): Replace usage of
	eval_condition_without_cm with eval_condition.
	* region-model.h
	(region_model::eval_condition_without_cm): Delete decl.

gcc/testsuite/ChangeLog:
	PR analyzer/101962
	* gcc.dg/analyzer/data-model-23.c (test_3): New test.

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