[PR c++/71965] silence multi-dim array init sorry without tf_error

[PR c++/71965] silence multi-dim array init sorry without tf_error

We shouldn't substitute templates into short-circuited-out concepts
constraints, but we do, and to add insult to injury, we issue a
sorry() error when a concept that shouldn't even have been substituted
attempts to perform a multi-dimensional array initialization with a
new{} expression.

Although fixing the requirements short-circuiting is probably too
risky at this point, we can get closer to the intended effect by
silencing that sorry just as we silence other errors.

for  gcc/cp/ChangeLog

	PR c++/71965
	* init.c (build_vec_init): Silence error, former sorry,
	without tf_error.

for  gcc/testsuite/ChangeLog

	PR c++/71965
	* g++.dg/concepts/pr71965.C: New.

From-SVN: r258749