c++: another build_new_1 folding fix [PR111929]

c++: another build_new_1 folding fix [PR111929]

In build_new_1, we also need to avoid folding 'outer_nelts_check' when
in a template context to prevent an ICE on the below testcase.  This
patch replaces the problematic fold_build2 call with build2 (we'll later
fold it if appropriate during cp_fully_fold).

In passing, this patch removes an unnecessary conversion of 'nelts'
since it should always already be a size_t (and 'convert' isn't the best
conversion entry point to use anyway since it lacks a complain parameter).

	PR c++/111929

gcc/cp/ChangeLog:

	* init.cc (build_new_1): Remove unnecessary call to convert
	on 'nelts'.  Use build2 instead of fold_build2 for
	'outer_nelts_checks'.

gcc/testsuite/ChangeLog:

	* g++.dg/template/non-dependent28a.C: New test.