ranger: fix small thinko in fur_list constructor

ranger: fix small thinko in fur_list constructor

The fur_list constructor for two ranges is leaving [1] in an undefined
state.  The reason we haven't noticed is because after all the
shuffling in the last cycle there are no remaining users of it
(similarly for fur_list(unsigned, irange *)).

Since it's very late in the cycle, I would prefer to fix this, rather
than removing unused constructors altogether.  Besides, we have uses
of them queued up for the next release.

gcc/ChangeLog:

	* gimple-range-fold.cc (fur_list::fur_list): Set m_local[1] correctly.