Bring fix for "when you ask for atomics and don't get it, abort configure" to release branches

[jsquyres]

Master PR is #3757. All it does is make this part of configure like other parts of configure: if a human asks for FOO and configure can't deliver FOO, then configure should abort.

Need to bring this to release branches:

• v2.0.x
• v2.x
• v3.0.x