return canonical Relational if only real assumption is missing

[smichr]

One of the reasons we can't return True from something like x > x - 1 is that this should only evaluate if x is real. But instead of leaving it unevaluated (as if to say nothing can be said) we could return x < oo or x > -oo. Basically, the same operator could be used with the appropriate oo on the rhs, e.g. x <= x + 1 -> x <= oo.