isl_local_space_substitute_seq: honor argument for the number of divs to modify
An argument for specifying the number of divs to modify was
introduced in
4a107ab (isl_local_space_substitute_seq: take argument for
the number of divs to modify, Sat Sep 29 19:45:57 2012 +0200),
but it was not actually taken into account, resulting in breakage
as soon as this argument was effectively used in
ad90fe4
(isl_aff_normalize: plug in divs with unit coefficient in other divs,
Sat Sep 29 20:11:32 2012 +0200).
Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>