c++: Prevent warnings for value-dependent exprs [PR96742]

c++: Prevent warnings for value-dependent exprs [PR96742]

Here, in r11-155, I changed the call to uses_template_parms to
type_dependent_expression_p_push to avoid a crash in C++98 in
value_dependent_expression_p on a non-constant expression.  But that
prompted a host of complaints that we now warn for value-dependent
expressions in templates.  Those warnings are technically valid, but
people still don't want them because they're awkward to avoid.  This
patch uses value_dependent_expression_p or type_dependent_expression_p.
But make sure that we don't ICE in value_dependent_expression_p by
checking potential_constant_expression first.

gcc/cp/ChangeLog:

	PR c++/96675
	PR c++/96742
	* pt.c (tsubst_copy_and_build): Call value_dependent_expression_p or
	type_dependent_expression_p instead of type_dependent_expression_p_push.
	But only call value_dependent_expression_p for expressions that are
	potential_constant_expression.

gcc/testsuite/ChangeLog:

	PR c++/96675
	PR c++/96742
	* g++.dg/warn/Wdiv-by-zero-3.C: Turn dg-warning into dg-bogus.
	* g++.dg/warn/Wtautological-compare3.C: New test.
	* g++.dg/warn/Wtype-limits5.C: New test.
	* g++.old-deja/g++.pt/crash10.C: Remove dg-warning.