Convert some evrp uses in DOM to the range_query API.

Convert some evrp uses in DOM to the range_query API.

DOM is the last remaining user of the evrp engine.  This patch converts
a few uses of the engine and vr-values into the new API.

There is one subtle change.  The call to vr_value's
op_with_constant_singleton_value_range can theoretically return
non-constants, unlike the range_query API which only returns constants.
In this particular case it doesn't matter because the symbolic stuff will
have been handled by the const_and_copies/avail_exprs read in the
SSA_NAME_VALUE copy immediately before.  I have verified this is the case
by asserting that all calls to op_with_constant_singleton_value_range at
this point return either NULL or an INTEGER_CST.

Tested on x86-64 Linux with a regstrap, as well as the aforementioned
assert.

gcc/ChangeLog:

	* gimple-ssa-evrp-analyze.h (class evrp_range_analyzer): Remove
	vrp_visit_cond_stmt.
	* tree-ssa-dom.c (cprop_operand): Convert to range_query API.
	(cprop_into_stmt): Same.
	(dom_opt_dom_walker::optimize_stmt): Same.