fb334765e2
Avoid endless run-time recursion for copying single-element tuples where the element type is by-value constructible from any type. * include/std/tuple (_NotSameTuple): New. * include/std/tuple (tuple(_UElements&&...): Use it. * testsuite/20_util/tuple/cons/element_accepts_anything_byval.cc: New. From-SVN: r236025