c++: keep destroying array after one dtor throws [PR66451]

c++: keep destroying array after one dtor throws [PR66451]

When we're cleaning up an array, if one destructor throws, we should still
try to clean up the rest of the array.  We can use TRY_CATCH_EXPR for this,
instead of a TARGET_EXPR like my other recent patches, because a destructor
call can't involve any temporaries that need to live longer.

I thought about only doing this when we call build_vec_delete_1 from
build_vec_init, but it seems appropriate for delete-expressions as well;
we've said that the array's lifetime is over, it makes sense to keep trying
to destroy it.  The standard isn't clear, but clang seems to agree with me.

	PR c++/66451

gcc/cp/ChangeLog:

	* init.c (build_vec_delete_1): Handle throwing dtor.
	(build_vec_init): Tell it we're in a cleanup already.

gcc/testsuite/ChangeLog:

	* g++.dg/eh/array3.C: New test.
	* g++.dg/eh/array1.C: Mark destructor as throw().
	* g++.dg/ipa/devirt-40.C: Likewise.
	* g++.dg/warn/pr83054.C: Likewise.
	* g++.dg/eh/delete1.C: Shorten array to one element.