remove extra division in mpq/aors.c

[Torbjorn Granlund]

Marc Glisse <marc.glisse at inria.fr> writes:

  Just to make my earlier remarks more constructive, 2 versions of what
  I was suggesting are attached.

The scalar division by dl isn't good, it is a very slow operation (think
~70 cycles on a modern CPU).  It might look cumbersome to test for 3 and
5 separately, but since the divisors come from gcd, these will be very
common cases, and 3 will be considerably mode common than 5.

I'll follow some of your suggestions, though.

-- 
Torbjörn